From a982795388c22561f42e726092b4d1ac72e7d2c1 Mon Sep 17 00:00:00 2001
From: duffyduck <info@hacker-net.de>
Date: Sat, 16 May 2026 23:47:17 +0200
Subject: [PATCH] Security-Hardening Runde 10: Pentest Runde 6 (8 Findings +
 struktureller Audit-Sweep)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

KRITISCH:
- emails/:id/thread bekommt canAccessCachedEmail
- customers/:customerId/representatives/search bekommt canAccessCustomer
  (Buchstaben-Brute-Force konnte sonst die Kunden-DB enumerieren)

HOCH:
- birthdays/upcoming: Portal-User → 403 (Name/E-Mail/Telefon/Geb-Datum
  aller Kunden leakte)
- contracts/:id/history (GET/POST/PUT/DELETE) bekommt canAccessContract
- mailbox-accounts / unread-count / contracts/:id/emails/folder-counts
  bekommen canAccessCustomer bzw. canAccessContract
- Vertreter-Vollmacht-Check ist jetzt live: neuer Helper
  getPortalAllowedCustomerIds() in accessControl.ts ruft
  hasAuthorization() für jedes vertretene Customer ab. Eingesetzt in
  getTasks/createSupportTicket/createCustomerReply/getAllTasks/
  getTaskStats und updateCustomerConsent. Widerrufene Vollmachten
  haben jetzt SOFORT keinen Zugriff mehr (vorher: bis JWT abläuft).

MITTEL:
- confirmPasswordReset speichert portalPasswordEncrypted nicht mehr
  beim Self-Service-Reset (war nur für Admin-OTPs gedacht); +
  portalPasswordMustChange=false explizit
- getCustomers pagination total reflektiert jetzt nur erlaubte IDs
  (über DB-Filter in customerService.getAllCustomers)

Audit-Sweep (defense in depth, falls Rolle versehentlich Update-
Permissions bekommt):
- 16 cachedEmail-Operationen (markAsRead, toggleStar, assign/unassign,
  save-as-pdf/invoice/contract-document, save-to, attachment-targets,
  trash-ops)
- 4 contract-Operationen (createFollowUp, createRenewal, snoozeContract,
  removeContractMeter)
- 12 sub-CRUD-Operationen (address/bankcard/document/meter
  update+delete, meter-reading add/update/delete/transfer)
- 2 representative-Operationen (add/remove)

Live-verifiziert: Portal-Customer-3 auf alle fremden IDs → 403,
Admin sieht alles, eigene Ressourcen weiterhin 200, Customer 1 mit
widerrufener Vollmacht für Customer 3 → 0 fremde Verträge in der
Response.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 .../src/controllers/birthday.controller.ts    |   7 ++
 .../src/controllers/cachedEmail.controller.ts |  62 ++++++----
 .../src/controllers/contract.controller.ts    |   6 +-
 .../controllers/contractHistory.controller.ts |   5 +
 .../controllers/contractTask.controller.ts    | 112 +++++++-----------
 .../src/controllers/customer.controller.ts    |  80 ++++++++-----
 backend/src/controllers/gdpr.controller.ts    |  14 +--
 backend/src/services/auth.service.ts          |   9 +-
 backend/src/services/customer.service.ts      |   9 +-
 backend/src/utils/accessControl.ts            |  28 +++++
 docs/todo.md                                  |  61 ++++++++++
 11 files changed, 256 insertions(+), 137 deletions(-)

diff --git a/backend/src/controllers/birthday.controller.ts b/backend/src/controllers/birthday.controller.ts
index a8f5508f..c26db5ca 100644
--- a/backend/src/controllers/birthday.controller.ts
+++ b/backend/src/controllers/birthday.controller.ts
@@ -11,6 +11,13 @@ import { createAuditLog } from '../services/audit.service.js';
  */
 export async function getUpcomingBirthdays(req: AuthRequest, res: Response) {
   try {
+    // Portal-Kunden haben hier nichts zu suchen. Endpoint listet Namen, E-Mail,
+    // Telefon und Geburtsdatum ALLER Kunden – ausschließlich Mitarbeiter-UI.
+    // Pentest Runde 6 (2026-05-16) – HOCH.
+    if (req.user?.isCustomerPortal) {
+      res.status(403).json({ success: false, error: 'Nicht erlaubt' });
+      return;
+    }
     const past = req.query.past ? parseInt(String(req.query.past)) : 7;
     const future = req.query.future ? parseInt(String(req.query.future)) : 30;
 
diff --git a/backend/src/controllers/cachedEmail.controller.ts b/backend/src/controllers/cachedEmail.controller.ts
index c41d479f..37b5e8fc 100644
--- a/backend/src/controllers/cachedEmail.controller.ts
+++ b/backend/src/controllers/cachedEmail.controller.ts
@@ -9,7 +9,7 @@ import { fetchAttachment, appendToSent, ImapCredentials } from '../services/imap
 import { getImapSmtpSettings } from '../services/emailProvider/emailProviderService.js';
 import { decrypt } from '../utils/encryption.js';
 import { logChange } from '../services/audit.service.js';
-import { ApiResponse } from '../types/index.js';
+import { ApiResponse, AuthRequest } from '../types/index.js';
 import { getCustomerTargets, getContractTargets, getIdentityDocumentTargets, getBankCardTargets, documentTargets } from '../config/documentTargets.config.js';
 import { generateEmailPdf } from '../services/pdfService.js';
 import { maybeActivateOnDeliveryConfirmation } from '../services/contractStatusScheduler.service.js';
@@ -17,7 +17,6 @@ import { DocumentType } from '@prisma/client';
 import prisma from '../lib/prisma.js';
 import path from 'path';
 import fs from 'fs';
-import { AuthRequest } from '../types/index.js';
 import {
   canAccessCustomer,
   canAccessContract,
@@ -139,9 +138,10 @@ export async function getEmail(req: AuthRequest, res: Response): Promise<void> {
 }
 
 // E-Mail als gelesen/ungelesen markieren
-export async function markAsRead(req: Request, res: Response): Promise<void> {
+export async function markAsRead(req: AuthRequest, res: Response): Promise<void> {
   try {
     const id = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, id))) return;
     const { isRead } = req.body;
 
     if (isRead) {
@@ -161,9 +161,10 @@ export async function markAsRead(req: Request, res: Response): Promise<void> {
 }
 
 // E-Mail Stern umschalten
-export async function toggleStar(req: Request, res: Response): Promise<void> {
+export async function toggleStar(req: AuthRequest, res: Response): Promise<void> {
   try {
     const id = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, id))) return;
     const isStarred = await cachedEmailService.toggleEmailStar(id);
 
     res.json({ success: true, data: { isStarred } } as ApiResponse);
@@ -179,10 +180,12 @@ export async function toggleStar(req: Request, res: Response): Promise<void> {
 // ==================== CONTRACT ASSIGNMENT ====================
 
 // E-Mail einem Vertrag zuordnen
-export async function assignToContract(req: Request, res: Response): Promise<void> {
+export async function assignToContract(req: AuthRequest, res: Response): Promise<void> {
   try {
     const emailId = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, emailId))) return;
     const { contractId } = req.body;
+    if (!(await canAccessContract(req, res, contractId))) return;
     const userId = (req as any).userId; // Falls Auth-Middleware userId setzt
 
     const email = await cachedEmailService.assignEmailToContract(emailId, contractId, userId);
@@ -198,9 +201,10 @@ export async function assignToContract(req: Request, res: Response): Promise<voi
 }
 
 // Vertragszuordnung aufheben
-export async function unassignFromContract(req: Request, res: Response): Promise<void> {
+export async function unassignFromContract(req: AuthRequest, res: Response): Promise<void> {
   try {
     const emailId = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, emailId))) return;
 
     const email = await cachedEmailService.unassignEmailFromContract(emailId);
 
@@ -233,9 +237,10 @@ export async function getFolderCounts(req: AuthRequest, res: Response): Promise<
 }
 
 // E-Mail-Anzahl pro Ordner für einen Vertrag
-export async function getContractFolderCounts(req: Request, res: Response): Promise<void> {
+export async function getContractFolderCounts(req: AuthRequest, res: Response): Promise<void> {
   try {
     const contractId = parseInt(req.params.contractId);
+    if (!(await canAccessContract(req, res, contractId))) return;
 
     const counts = await cachedEmailService.getFolderCountsForContract(contractId);
 
@@ -611,9 +616,10 @@ export async function downloadAttachment(req: AuthRequest, res: Response): Promi
 // ==================== MAILBOX ACCOUNTS ====================
 
 // Mailbox-Konten eines Kunden abrufen
-export async function getMailboxAccounts(req: Request, res: Response): Promise<void> {
+export async function getMailboxAccounts(req: AuthRequest, res: Response): Promise<void> {
   try {
     const customerId = parseInt(req.params.customerId);
+    if (!(await canAccessCustomer(req, res, customerId))) return;
 
     const accounts = await cachedEmailService.getMailboxAccountsForCustomer(customerId);
 
@@ -686,9 +692,10 @@ export async function syncMailboxStatus(req: AuthRequest, res: Response): Promis
 }
 
 // E-Mail-Thread abrufen
-export async function getThread(req: Request, res: Response): Promise<void> {
+export async function getThread(req: AuthRequest, res: Response): Promise<void> {
   try {
     const id = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, id))) return;
 
     const thread = await cachedEmailService.getEmailThread(id);
 
@@ -780,7 +787,7 @@ export async function getMailboxCredentials(req: AuthRequest, res: Response): Pr
 }
 
 // Ungelesene E-Mails zählen
-export async function getUnreadCount(req: Request, res: Response): Promise<void> {
+export async function getUnreadCount(req: AuthRequest, res: Response): Promise<void> {
   try {
     const customerId = req.query.customerId ? parseInt(req.query.customerId as string) : undefined;
     const contractId = req.query.contractId ? parseInt(req.query.contractId as string) : undefined;
@@ -788,8 +795,10 @@ export async function getUnreadCount(req: Request, res: Response): Promise<void>
     let count = 0;
 
     if (customerId) {
+      if (!(await canAccessCustomer(req, res, customerId))) return;
       count = await cachedEmailService.getUnreadCountForCustomer(customerId);
     } else if (contractId) {
+      if (!(await canAccessContract(req, res, contractId))) return;
       count = await cachedEmailService.getUnreadCountForContract(contractId);
     }
 
@@ -804,9 +813,10 @@ export async function getUnreadCount(req: Request, res: Response): Promise<void>
 }
 
 // E-Mail in Papierkorb verschieben (nur Admin)
-export async function deleteEmail(req: Request, res: Response): Promise<void> {
+export async function deleteEmail(req: AuthRequest, res: Response): Promise<void> {
   try {
     const id = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, id))) return;
 
     // Prüfen ob E-Mail existiert
     const email = await cachedEmailService.getCachedEmailById(id);
@@ -841,9 +851,10 @@ export async function deleteEmail(req: Request, res: Response): Promise<void> {
 // ==================== TRASH OPERATIONS ====================
 
 // Papierkorb-E-Mails für einen Kunden abrufen
-export async function getTrashEmails(req: Request, res: Response): Promise<void> {
+export async function getTrashEmails(req: AuthRequest, res: Response): Promise<void> {
   try {
     const customerId = parseInt(req.params.customerId);
+    if (!(await canAccessCustomer(req, res, customerId))) return;
 
     const emails = await cachedEmailService.getTrashEmails(customerId);
 
@@ -858,9 +869,10 @@ export async function getTrashEmails(req: Request, res: Response): Promise<void>
 }
 
 // Papierkorb-Anzahl für einen Kunden
-export async function getTrashCount(req: Request, res: Response): Promise<void> {
+export async function getTrashCount(req: AuthRequest, res: Response): Promise<void> {
   try {
     const customerId = parseInt(req.params.customerId);
+    if (!(await canAccessCustomer(req, res, customerId))) return;
 
     const count = await cachedEmailService.getTrashCount(customerId);
 
@@ -875,9 +887,10 @@ export async function getTrashCount(req: Request, res: Response): Promise<void>
 }
 
 // E-Mail aus Papierkorb wiederherstellen
-export async function restoreEmail(req: Request, res: Response): Promise<void> {
+export async function restoreEmail(req: AuthRequest, res: Response): Promise<void> {
   try {
     const id = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, id))) return;
 
     const result = await cachedEmailService.restoreEmailFromTrash(id);
 
@@ -900,9 +913,10 @@ export async function restoreEmail(req: Request, res: Response): Promise<void> {
 }
 
 // E-Mail endgültig löschen (aus Papierkorb)
-export async function permanentDeleteEmail(req: Request, res: Response): Promise<void> {
+export async function permanentDeleteEmail(req: AuthRequest, res: Response): Promise<void> {
   try {
     const id = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, id))) return;
 
     const result = await cachedEmailService.permanentDeleteEmail(id);
 
@@ -927,9 +941,10 @@ export async function permanentDeleteEmail(req: Request, res: Response): Promise
 // ==================== ATTACHMENT TARGETS ====================
 
 // Verfügbare Dokumenten-Ziele für E-Mail-Anhänge abrufen
-export async function getAttachmentTargets(req: Request, res: Response): Promise<void> {
+export async function getAttachmentTargets(req: AuthRequest, res: Response): Promise<void> {
   try {
     const emailId = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, emailId))) return;
 
     // E-Mail mit StressfreiEmail laden
     const email = await cachedEmailService.getCachedEmailById(emailId);
@@ -1109,9 +1124,10 @@ export async function getAttachmentTargets(req: Request, res: Response): Promise
 }
 
 // E-Mail-Anhang in ein Dokumentenfeld speichern
-export async function saveAttachmentTo(req: Request, res: Response): Promise<void> {
+export async function saveAttachmentTo(req: AuthRequest, res: Response): Promise<void> {
   try {
     const emailId = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, emailId))) return;
     const filename = decodeURIComponent(req.params.filename);
     const { entityType, entityId, targetKey } = req.body;
 
@@ -1396,9 +1412,10 @@ export async function saveAttachmentTo(req: Request, res: Response): Promise<voi
 // ==================== SAVE EMAIL AS PDF ====================
 
 // E-Mail als PDF exportieren und in Dokumentenfeld speichern
-export async function saveEmailAsPdf(req: Request, res: Response): Promise<void> {
+export async function saveEmailAsPdf(req: AuthRequest, res: Response): Promise<void> {
   try {
     const emailId = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, emailId))) return;
     const { entityType, entityId, targetKey } = req.body;
 
     console.log('[saveEmailAsPdf] Request:', { emailId, entityType, entityId, targetKey });
@@ -1643,9 +1660,10 @@ export async function saveEmailAsPdf(req: Request, res: Response): Promise<void>
 // ==================== SAVE EMAIL AS INVOICE ====================
 
 // E-Mail als PDF exportieren und als Rechnung speichern
-export async function saveEmailAsInvoice(req: Request, res: Response): Promise<void> {
+export async function saveEmailAsInvoice(req: AuthRequest, res: Response): Promise<void> {
   try {
     const emailId = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, emailId))) return;
     const { invoiceDate, invoiceType, notes } = req.body;
 
     console.log('[saveEmailAsInvoice] Request:', { emailId, invoiceDate, invoiceType, notes });
@@ -1769,9 +1787,10 @@ export async function saveEmailAsInvoice(req: Request, res: Response): Promise<v
 // ==================== SAVE ATTACHMENT AS INVOICE ====================
 
 // E-Mail-Anhang als Rechnung speichern
-export async function saveAttachmentAsInvoice(req: Request, res: Response): Promise<void> {
+export async function saveAttachmentAsInvoice(req: AuthRequest, res: Response): Promise<void> {
   try {
     const emailId = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, emailId))) return;
     const filename = decodeURIComponent(req.params.filename);
     const { invoiceDate, invoiceType, notes } = req.body;
 
@@ -1932,9 +1951,10 @@ export async function saveAttachmentAsInvoice(req: Request, res: Response): Prom
  * Anhang einer E-Mail als Vertragsdokument (ContractDocument) speichern.
  * Nutzt die flexible ContractDocument-Tabelle mit documentType (Auftragsformular, Lieferbestätigung, etc.)
  */
-export async function saveAttachmentAsContractDocument(req: Request, res: Response): Promise<void> {
+export async function saveAttachmentAsContractDocument(req: AuthRequest, res: Response): Promise<void> {
   try {
     const emailId = parseInt(req.params.id);
+    if (!(await canAccessCachedEmail(req, res, emailId))) return;
     const filename = decodeURIComponent(req.params.filename);
     const { documentType, notes } = req.body;
 
diff --git a/backend/src/controllers/contract.controller.ts b/backend/src/controllers/contract.controller.ts
index ac429f51..78e2d9c1 100644
--- a/backend/src/controllers/contract.controller.ts
+++ b/backend/src/controllers/contract.controller.ts
@@ -211,6 +211,7 @@ export async function deleteContract(req: Request, res: Response): Promise<void>
 export async function createFollowUp(req: AuthRequest, res: Response): Promise<void> {
   try {
     const previousContractId = parseInt(req.params.id);
+    if (!(await canAccessContract(req, res, previousContractId))) return;
 
     // Vorgängervertrag laden für Vertragsnummer
     const previousContract = await prisma.contract.findUnique({
@@ -264,6 +265,7 @@ export async function createFollowUp(req: AuthRequest, res: Response): Promise<v
 export async function createRenewal(req: AuthRequest, res: Response): Promise<void> {
   try {
     const previousContractId = parseInt(req.params.id);
+    if (!(await canAccessContract(req, res, previousContractId))) return;
 
     const previousContract = await prisma.contract.findUnique({
       where: { id: previousContractId },
@@ -526,6 +528,7 @@ export async function removeContractMeter(req: AuthRequest, res: Response): Prom
   try {
     const contractMeterId = parseInt(req.params.contractMeterId);
     const contractId = parseInt(req.params.id);
+    if (!(await canAccessContract(req, res, contractId))) return;
     await prisma.contractMeter.delete({ where: { id: contractMeterId } });
     await logChange({
       req, action: 'DELETE', resourceType: 'ContractMeter',
@@ -649,9 +652,10 @@ export async function deleteContractDocument(req: AuthRequest, res: Response): P
 
 // ==================== SNOOZE (VERTRAG ZURÜCKSTELLEN) ====================
 
-export async function snoozeContract(req: Request, res: Response): Promise<void> {
+export async function snoozeContract(req: AuthRequest, res: Response): Promise<void> {
   try {
     const id = parseInt(req.params.id);
+    if (!(await canAccessContract(req, res, id))) return;
     const { nextReviewDate, months } = req.body;
 
     let reviewDate: Date | null = null;
diff --git a/backend/src/controllers/contractHistory.controller.ts b/backend/src/controllers/contractHistory.controller.ts
index 85755b18..a80b1e5c 100644
--- a/backend/src/controllers/contractHistory.controller.ts
+++ b/backend/src/controllers/contractHistory.controller.ts
@@ -2,10 +2,12 @@ import { Request, Response } from 'express';
 import * as contractHistoryService from '../services/contractHistory.service.js';
 import { logChange } from '../services/audit.service.js';
 import { ApiResponse, AuthRequest } from '../types/index.js';
+import { canAccessContract } from '../utils/accessControl.js';
 
 export async function getHistoryEntries(req: AuthRequest, res: Response): Promise<void> {
   try {
     const contractId = parseInt(req.params.contractId);
+    if (!(await canAccessContract(req, res, contractId))) return;
     const entries = await contractHistoryService.getHistoryEntries(contractId);
     res.json({ success: true, data: entries } as ApiResponse);
   } catch (error) {
@@ -19,6 +21,7 @@ export async function getHistoryEntries(req: AuthRequest, res: Response): Promis
 export async function createHistoryEntry(req: AuthRequest, res: Response): Promise<void> {
   try {
     const contractId = parseInt(req.params.contractId);
+    if (!(await canAccessContract(req, res, contractId))) return;
     const { title, description } = req.body;
 
     if (!title || typeof title !== 'string' || title.trim().length === 0) {
@@ -54,6 +57,7 @@ export async function createHistoryEntry(req: AuthRequest, res: Response): Promi
 export async function updateHistoryEntry(req: AuthRequest, res: Response): Promise<void> {
   try {
     const contractId = parseInt(req.params.contractId);
+    if (!(await canAccessContract(req, res, contractId))) return;
     const entryId = parseInt(req.params.entryId);
     const { title, description } = req.body;
 
@@ -80,6 +84,7 @@ export async function updateHistoryEntry(req: AuthRequest, res: Response): Promi
 export async function deleteHistoryEntry(req: AuthRequest, res: Response): Promise<void> {
   try {
     const contractId = parseInt(req.params.contractId);
+    if (!(await canAccessContract(req, res, contractId))) return;
     const entryId = parseInt(req.params.entryId);
 
     await contractHistoryService.deleteHistoryEntry(contractId, entryId);
diff --git a/backend/src/controllers/contractTask.controller.ts b/backend/src/controllers/contractTask.controller.ts
index ad8f5987..1718e63a 100644
--- a/backend/src/controllers/contractTask.controller.ts
+++ b/backend/src/controllers/contractTask.controller.ts
@@ -5,6 +5,7 @@ import * as customerService from '../services/customer.service.js';
 import * as appSettingService from '../services/appSetting.service.js';
 import { logChange } from '../services/audit.service.js';
 import { ApiResponse, AuthRequest } from '../types/index.js';
+import { canAccessContract, getPortalAllowedCustomerIds } from '../utils/accessControl.js';
 
 // ==================== ALL TASKS (Dashboard & Task List) ====================
 
@@ -12,12 +13,13 @@ export async function getAllTasks(req: AuthRequest, res: Response): Promise<void
   try {
     const { status, customerId } = req.query;
 
-    // Für Kundenportal: Filter auf erlaubte Kunden
+    // Für Kundenportal: Filter auf erlaubte Kunden (mit Live-Vollmacht-Check)
+    const allowedIds = await getPortalAllowedCustomerIds(req);
     let customerPortalCustomerIds: number[] | undefined;
     let customerPortalEmails: string[] | undefined;
 
-    if (req.user?.isCustomerPortal && req.user.customerId) {
-      customerPortalCustomerIds = [req.user.customerId, ...(req.user.representedCustomerIds || [])];
+    if (allowedIds) {
+      customerPortalCustomerIds = allowedIds;
       const customers = await customerService.getCustomersByIds(customerPortalCustomerIds);
       customerPortalEmails = customers
         .map((c: { id: number; portalEmail: string | null }) => c.portalEmail)
@@ -42,12 +44,13 @@ export async function getAllTasks(req: AuthRequest, res: Response): Promise<void
 
 export async function getTaskStats(req: AuthRequest, res: Response): Promise<void> {
   try {
-    // Für Kundenportal: Filter auf erlaubte Kunden
+    // Für Kundenportal: Filter auf erlaubte Kunden (mit Live-Vollmacht-Check)
+    const allowedIds = await getPortalAllowedCustomerIds(req);
     let customerPortalCustomerIds: number[] | undefined;
     let customerPortalEmails: string[] | undefined;
 
-    if (req.user?.isCustomerPortal && req.user.customerId) {
-      customerPortalCustomerIds = [req.user.customerId, ...(req.user.representedCustomerIds || [])];
+    if (allowedIds) {
+      customerPortalCustomerIds = allowedIds;
       const customers = await customerService.getCustomersByIds(customerPortalCustomerIds);
       customerPortalEmails = customers
         .map((c: { id: number; portalEmail: string | null }) => c.portalEmail)
@@ -75,33 +78,17 @@ export async function getTasks(req: AuthRequest, res: Response): Promise<void> {
     const contractId = parseInt(req.params.contractId);
     const { status } = req.query;
 
-    // Prüfe Zugriff auf den Vertrag
-    const contract = await contractService.getContractById(contractId);
-    if (!contract) {
-      res.status(404).json({
-        success: false,
-        error: 'Vertrag nicht gefunden',
-      } as ApiResponse);
-      return;
-    }
+    // Zentraler canAccessContract-Check inkl. Live-Vollmacht-Prüfung über
+    // hasAuthorization (Pentest Runde 6 – HOCH-04: widerrufene Vollmachten
+    // hatten vorher weiter Zugriff, weil nur representedCustomerIds-Array
+    // konsultiert wurde, ohne Status-Check).
+    if (!(await canAccessContract(req, res, contractId))) return;
 
-    // Für Kundenportal: Zugriffsprüfung
-    if (req.user?.isCustomerPortal && req.user.customerId) {
-      const allowedCustomerIds = [req.user.customerId, ...(req.user.representedCustomerIds || [])];
-      if (!allowedCustomerIds.includes(contract.customerId)) {
-        res.status(403).json({
-          success: false,
-          error: 'Kein Zugriff auf diesen Vertrag',
-        } as ApiResponse);
-        return;
-      }
-    }
-
-    // Für Kundenportal-Benutzer: Lade E-Mails der erlaubten Kunden
+    // Für Kundenportal-Benutzer: Lade E-Mails der erlaubten Kunden (mit Live-Vollmacht-Check)
     let customerPortalEmails: string[] | undefined;
-    if (req.user?.isCustomerPortal && req.user.customerId) {
-      const allowedCustomerIds = [req.user.customerId, ...(req.user.representedCustomerIds || [])];
-      const customers = await customerService.getCustomersByIds(allowedCustomerIds);
+    const allowedIds = await getPortalAllowedCustomerIds(req);
+    if (allowedIds) {
+      const customers = await customerService.getCustomersByIds(allowedIds);
       customerPortalEmails = customers
         .map((c: { id: number; portalEmail: string | null }) => c.portalEmail)
         .filter((email: string | null): email is string => !!email);
@@ -187,27 +174,8 @@ export async function createSupportTicket(req: AuthRequest, res: Response): Prom
       return;
     }
 
-    // Prüfe Zugriff auf den Vertrag
-    const contract = await contractService.getContractById(contractId);
-    if (!contract) {
-      res.status(404).json({
-        success: false,
-        error: 'Vertrag nicht gefunden',
-      } as ApiResponse);
-      return;
-    }
-
-    // Zugriffsprüfung für Kundenportal
-    if (req.user?.customerId) {
-      const allowedCustomerIds = [req.user.customerId, ...(req.user.representedCustomerIds || [])];
-      if (!allowedCustomerIds.includes(contract.customerId)) {
-        res.status(403).json({
-          success: false,
-          error: 'Kein Zugriff auf diesen Vertrag',
-        } as ApiResponse);
-        return;
-      }
-    }
+    // canAccessContract inkl. Live-Vollmacht-Prüfung (siehe getTasks).
+    if (!(await canAccessContract(req, res, contractId))) return;
 
     const createdBy = req.user?.email;
 
@@ -376,24 +344,7 @@ export async function createCustomerReply(req: AuthRequest, res: Response): Prom
       return;
     }
 
-    // Prüfe ob der Kunde berechtigt ist (eigenes Ticket oder freigegebener Kunde)
-    if (req.user?.isCustomerPortal && req.user.customerId) {
-      const allowedCustomerIds = [req.user.customerId, ...(req.user.representedCustomerIds || [])];
-      const customers = await customerService.getCustomersByIds(allowedCustomerIds);
-      const allowedEmails = customers
-        .map((c: { id: number; portalEmail: string | null }) => c.portalEmail)
-        .filter((email: string | null): email is string => !!email);
-
-      // Task muss entweder visibleInPortal sein ODER vom Kunden erstellt worden sein
-      const isOwnTask = task.createdBy && allowedEmails.includes(task.createdBy);
-      if (!task.visibleInPortal && !isOwnTask) {
-        res.status(403).json({
-          success: false,
-          error: 'Kein Zugriff auf diese Anfrage',
-        } as ApiResponse);
-        return;
-      }
-    } else {
+    if (!req.user?.isCustomerPortal || !req.user.customerId) {
       res.status(403).json({
         success: false,
         error: 'Nur für Kundenportal-Benutzer',
@@ -401,6 +352,27 @@ export async function createCustomerReply(req: AuthRequest, res: Response): Prom
       return;
     }
 
+    // Strikter Owner-Check über den Vertrag (mit Live-Vollmacht-Prüfung
+    // via hasAuthorization, Pentest Runde 6 – HOCH-04). Damit kann ein
+    // Portal-User keine fremde Task-ID mit visibleInPortal=true abgreifen.
+    if (!(await canAccessContract(req, res, task.contractId))) return;
+
+    // Zusätzlich: portal-User darf nur antworten, wenn die Task von ihm
+    // initiiert wurde ODER explizit für ihn sichtbar markiert ist.
+    const allowedCustomerIds = [req.user.customerId, ...(req.user.representedCustomerIds || [])];
+    const customers = await customerService.getCustomersByIds(allowedCustomerIds);
+    const allowedEmails = customers
+      .map((c: { id: number; portalEmail: string | null }) => c.portalEmail)
+      .filter((email: string | null): email is string => !!email);
+    const isOwnTask = task.createdBy && allowedEmails.includes(task.createdBy);
+    if (!task.visibleInPortal && !isOwnTask) {
+      res.status(403).json({
+        success: false,
+        error: 'Kein Zugriff auf diese Anfrage',
+      } as ApiResponse);
+      return;
+    }
+
     const createdBy = req.user?.email;
 
     const subtask = await contractTaskService.createSubtask({
diff --git a/backend/src/controllers/customer.controller.ts b/backend/src/controllers/customer.controller.ts
index 8d469340..1291deb0 100644
--- a/backend/src/controllers/customer.controller.ts
+++ b/backend/src/controllers/customer.controller.ts
@@ -18,30 +18,28 @@ import {
   canAccessBankCard,
   canAccessIdentityDocument,
   canAccessCustomer,
+  getPortalAllowedCustomerIds,
 } from '../utils/accessControl.js';
 
 // Customer CRUD
 export async function getCustomers(req: AuthRequest, res: Response): Promise<void> {
   try {
     const { search, type, page, limit } = req.query;
+
+    // Portal-User dürfen nur ihre eigenen + vertretene Kunden (mit aktiver
+    // Vollmacht) sehen. Wir geben die Liste direkt als DB-Filter mit, damit
+    // auch `pagination.total` nur über diese IDs zählt (Pentest Runde 6
+    // MITTEL-02: `total: 4271` leakte vorher die globale Kunden-Zahl).
+    const allowedIds = await getPortalAllowedCustomerIds(req);
+
     const result = await customerService.getAllCustomers({
       search: search as string,
       type: type as 'PRIVATE' | 'BUSINESS',
       page: page ? parseInt(page as string) : undefined,
       limit: limit ? parseInt(limit as string) : undefined,
+      allowedIds: allowedIds ?? undefined,
     });
-    let customers = result.customers as any[];
-
-    // Portal-Kunden: Liste auf eigenen + vertretene Kunden einschränken.
-    // Ohne diesen Filter würde der List-Endpoint die komplette Kundendatenbank
-    // an einen einzelnen Portal-Account preisgeben.
-    if (req.user?.isCustomerPortal) {
-      const allowedIds = new Set<number>();
-      if (req.user.customerId) allowedIds.add(req.user.customerId);
-      const represented = (req.user as any).representedCustomerIds || [];
-      for (const id of represented) allowedIds.add(id);
-      customers = customers.filter((c) => allowedIds.has(c.id));
-    }
+    const customers = result.customers as any[];
 
     // Portal-Kunden oder andere Rollen sehen kein portalPasswordEncrypted
     const canSeePasswords = req.user?.permissions?.includes('customers:update') ?? false;
@@ -233,9 +231,10 @@ export async function createAddress(req: AuthRequest, res: Response): Promise<vo
   }
 }
 
-export async function updateAddress(req: Request, res: Response): Promise<void> {
+export async function updateAddress(req: AuthRequest, res: Response): Promise<void> {
   try {
     const addressId = parseInt(req.params.id);
+    if (!(await canAccessAddress(req, res, addressId))) return;
     const data = req.body;
 
     // Vorherigen Stand laden für Audit
@@ -296,9 +295,10 @@ export async function updateAddress(req: Request, res: Response): Promise<void>
   }
 }
 
-export async function deleteAddress(req: Request, res: Response): Promise<void> {
+export async function deleteAddress(req: AuthRequest, res: Response): Promise<void> {
   try {
     const addressId = parseInt(req.params.id);
+    if (!(await canAccessAddress(req, res, addressId))) return;
     const addr = await prisma.address.findUnique({ where: { id: addressId }, select: { customerId: true } });
     const customerId = addr?.customerId;
     await customerService.deleteAddress(addressId);
@@ -350,9 +350,10 @@ export async function createBankCard(req: AuthRequest, res: Response): Promise<v
   }
 }
 
-export async function updateBankCard(req: Request, res: Response): Promise<void> {
+export async function updateBankCard(req: AuthRequest, res: Response): Promise<void> {
   try {
     const cardId = parseInt(req.params.id);
+    if (!(await canAccessBankCard(req, res, cardId))) return;
     const data = req.body;
 
     // Vorherigen Stand laden für Audit
@@ -408,9 +409,10 @@ export async function updateBankCard(req: Request, res: Response): Promise<void>
   }
 }
 
-export async function deleteBankCard(req: Request, res: Response): Promise<void> {
+export async function deleteBankCard(req: AuthRequest, res: Response): Promise<void> {
   try {
     const cardId = parseInt(req.params.id);
+    if (!(await canAccessBankCard(req, res, cardId))) return;
     const card = await prisma.bankCard.findUnique({ where: { id: cardId }, select: { customerId: true } });
     const customerId = card?.customerId;
     await customerService.deleteBankCard(cardId);
@@ -462,9 +464,10 @@ export async function createDocument(req: AuthRequest, res: Response): Promise<v
   }
 }
 
-export async function updateDocument(req: Request, res: Response): Promise<void> {
+export async function updateDocument(req: AuthRequest, res: Response): Promise<void> {
   try {
     const docId = parseInt(req.params.id);
+    if (!(await canAccessIdentityDocument(req, res, docId))) return;
     const data = req.body;
 
     // Vorherigen Stand laden für Audit
@@ -526,9 +529,10 @@ export async function updateDocument(req: Request, res: Response): Promise<void>
   }
 }
 
-export async function deleteDocument(req: Request, res: Response): Promise<void> {
+export async function deleteDocument(req: AuthRequest, res: Response): Promise<void> {
   try {
     const docId = parseInt(req.params.id);
+    if (!(await canAccessIdentityDocument(req, res, docId))) return;
     const doc = await prisma.identityDocument.findUnique({ where: { id: docId }, select: { customerId: true } });
     const customerId = doc?.customerId;
     await customerService.deleteDocument(docId);
@@ -580,9 +584,10 @@ export async function createMeter(req: AuthRequest, res: Response): Promise<void
   }
 }
 
-export async function updateMeter(req: Request, res: Response): Promise<void> {
+export async function updateMeter(req: AuthRequest, res: Response): Promise<void> {
   try {
     const meterId = parseInt(req.params.id);
+    if (!(await canAccessMeter(req, res, meterId))) return;
     const data = req.body;
 
     // Vorherigen Stand laden für Audit
@@ -637,9 +642,10 @@ export async function updateMeter(req: Request, res: Response): Promise<void> {
   }
 }
 
-export async function deleteMeter(req: Request, res: Response): Promise<void> {
+export async function deleteMeter(req: AuthRequest, res: Response): Promise<void> {
   try {
     const meterId = parseInt(req.params.id);
+    if (!(await canAccessMeter(req, res, meterId))) return;
     await customerService.deleteMeter(meterId);
     await logChange({
       req, action: 'DELETE', resourceType: 'Meter',
@@ -667,10 +673,11 @@ export async function getMeterReadings(req: AuthRequest, res: Response): Promise
   }
 }
 
-export async function addMeterReading(req: Request, res: Response): Promise<void> {
+export async function addMeterReading(req: AuthRequest, res: Response): Promise<void> {
   try {
     const { readingDate, value, valueNt, unit, notes } = req.body;
     const meterId = parseInt(req.params.meterId);
+    if (!(await canAccessMeter(req, res, meterId))) return;
     const reading = await customerService.addMeterReading(meterId, {
       readingDate: new Date(readingDate),
       value: parseFloat(value),
@@ -703,8 +710,10 @@ export async function addMeterReading(req: Request, res: Response): Promise<void
   }
 }
 
-export async function updateMeterReading(req: Request, res: Response): Promise<void> {
+export async function updateMeterReading(req: AuthRequest, res: Response): Promise<void> {
   try {
+    const meterId = parseInt(req.params.meterId);
+    if (!(await canAccessMeter(req, res, meterId))) return;
     const { readingDate, value, valueNt, unit, notes } = req.body;
     const updateData: Record<string, unknown> = {};
     if (readingDate !== undefined) updateData.readingDate = new Date(readingDate);
@@ -714,7 +723,7 @@ export async function updateMeterReading(req: Request, res: Response): Promise<v
     if (notes !== undefined) updateData.notes = notes;
 
     const reading = await customerService.updateMeterReading(
-      parseInt(req.params.meterId),
+      meterId,
       parseInt(req.params.readingId),
       updateData as any
     );
@@ -732,13 +741,12 @@ export async function updateMeterReading(req: Request, res: Response): Promise<v
   }
 }
 
-export async function deleteMeterReading(req: Request, res: Response): Promise<void> {
+export async function deleteMeterReading(req: AuthRequest, res: Response): Promise<void> {
   try {
+    const meterId = parseInt(req.params.meterId);
+    if (!(await canAccessMeter(req, res, meterId))) return;
     const readingId = parseInt(req.params.readingId);
-    await customerService.deleteMeterReading(
-      parseInt(req.params.meterId),
-      readingId
-    );
+    await customerService.deleteMeterReading(meterId, readingId);
     await logChange({
       req, action: 'DELETE', resourceType: 'MeterReading',
       resourceId: readingId.toString(),
@@ -839,6 +847,7 @@ export async function getMyMeters(req: AuthRequest, res: Response): Promise<void
 export async function markReadingTransferred(req: AuthRequest, res: Response): Promise<void> {
   try {
     const meterId = parseInt(req.params.meterId);
+    if (!(await canAccessMeter(req, res, meterId))) return;
     const readingId = parseInt(req.params.readingId);
 
     const reading = await prisma.meterReading.update({
@@ -1128,9 +1137,10 @@ export async function getRepresentatives(req: AuthRequest, res: Response): Promi
   }
 }
 
-export async function addRepresentative(req: Request, res: Response): Promise<void> {
+export async function addRepresentative(req: AuthRequest, res: Response): Promise<void> {
   try {
     const customerId = parseInt(req.params.customerId);
+    if (!(await canAccessCustomer(req, res, customerId))) return;
     const { representativeId, notes } = req.body;
     const representative = await customerService.addRepresentative(
       customerId,
@@ -1152,9 +1162,10 @@ export async function addRepresentative(req: Request, res: Response): Promise<vo
   }
 }
 
-export async function removeRepresentative(req: Request, res: Response): Promise<void> {
+export async function removeRepresentative(req: AuthRequest, res: Response): Promise<void> {
   try {
     const customerId = parseInt(req.params.customerId);
+    if (!(await canAccessCustomer(req, res, customerId))) return;
     await customerService.removeRepresentative(
       customerId,
       parseInt(req.params.representativeId)
@@ -1173,8 +1184,13 @@ export async function removeRepresentative(req: Request, res: Response): Promise
   }
 }
 
-export async function searchForRepresentative(req: Request, res: Response): Promise<void> {
+export async function searchForRepresentative(req: AuthRequest, res: Response): Promise<void> {
   try {
+    // KRITISCH (Pentest Runde 6): ohne canAccessCustomer kann ein Portal-User
+    // mit beliebigem :customerId-Pfad alle Kunden durchsuchen → komplette
+    // Kunden-DB-Enumeration via Buchstaben-Brute-Force.
+    const customerId = parseInt(req.params.customerId);
+    if (!(await canAccessCustomer(req, res, customerId))) return;
     const { search } = req.query;
     if (!search || typeof search !== 'string' || search.length < 2) {
       res.json({ success: true, data: [] } as ApiResponse);
@@ -1182,7 +1198,7 @@ export async function searchForRepresentative(req: Request, res: Response): Prom
     }
     const customers = await customerService.searchCustomersForRepresentative(
       search,
-      parseInt(req.params.customerId)
+      customerId,
     );
     res.json({ success: true, data: customers } as ApiResponse);
   } catch (error) {
diff --git a/backend/src/controllers/gdpr.controller.ts b/backend/src/controllers/gdpr.controller.ts
index 8712b19c..dda65d2f 100644
--- a/backend/src/controllers/gdpr.controller.ts
+++ b/backend/src/controllers/gdpr.controller.ts
@@ -279,17 +279,9 @@ export async function updateCustomerConsent(req: AuthRequest, res: Response) {
       });
     }
 
-    // Portal: nur eigene + vertretene Kunden
-    const allowed = [
-      (req.user as any).customerId,
-      ...((req.user as any).representedCustomerIds || []),
-    ];
-    if (!allowed.includes(customerId)) {
-      return res.status(403).json({
-        success: false,
-        error: 'Keine Berechtigung für diesen Kunden',
-      });
-    }
+    // canAccessCustomer inkl. Live-Vollmacht-Check (Pentest Runde 6 HOCH-04:
+    // widerrufene Vollmachten hatten vorher noch Zugriff)
+    if (!(await canAccessCustomer(req, res, customerId))) return;
 
     if (!Object.values(ConsentType).includes(consentType)) {
       return res.status(400).json({ success: false, error: 'Ungültiger Consent-Typ' });
diff --git a/backend/src/services/auth.service.ts b/backend/src/services/auth.service.ts
index c247be66..693b78df 100644
--- a/backend/src/services/auth.service.ts
+++ b/backend/src/services/auth.service.ts
@@ -782,11 +782,18 @@ export async function confirmPasswordReset(token: string, newPassword: string):
       where: { id: customer.id },
       data: {
         portalPasswordHash: hash,
-        portalPasswordEncrypted: encrypt(newPassword),
+        // Pentest Runde 6 (MITTEL-01): Beim Self-Service-Reset speichern wir
+        // KEINEN Klartext mehr. Encrypted-Feld ist nur für Admin-generierte
+        // Einmalpasswörter sinnvoll (damit Admin sie in der UI sehen + per
+        // Mail versenden kann); für ein vom Kunden selbst gesetztes Passwort
+        // ist Klartext-Speicherung ein unnötiges Recover-Risiko bei DB+Key-Leak.
+        portalPasswordEncrypted: null,
         portalPasswordResetToken: null,
         portalPasswordResetExpiresAt: null,
         // Alle bestehenden Portal-Sessions kicken
         portalTokenInvalidatedAt: new Date(),
+        // OTP-Flow-Flag ist nach selbstgesetztem Passwort definitiv aus
+        portalPasswordMustChange: false,
       },
     });
     return;
diff --git a/backend/src/services/customer.service.ts b/backend/src/services/customer.service.ts
index 755abf7b..c722253e 100644
--- a/backend/src/services/customer.service.ts
+++ b/backend/src/services/customer.service.ts
@@ -22,10 +22,13 @@ export interface CustomerFilters {
   type?: CustomerType;
   page?: number;
   limit?: number;
+  // Wenn gesetzt: nur Customer mit id in dieser Liste. Für Portal-User, damit
+  // weder Liste noch pagination.total die globale Kunden-Zahl preisgibt.
+  allowedIds?: number[];
 }
 
 export async function getAllCustomers(filters: CustomerFilters) {
-  const { search, type, page = 1, limit = 20 } = filters;
+  const { search, type, page = 1, limit = 20, allowedIds } = filters;
   const { skip, take } = paginate(page, limit);
 
   const where: Record<string, unknown> = {};
@@ -34,6 +37,10 @@ export async function getAllCustomers(filters: CustomerFilters) {
     where.type = type;
   }
 
+  if (allowedIds) {
+    where.id = { in: allowedIds };
+  }
+
   if (search) {
     where.OR = [
       { firstName: { contains: search } },
diff --git a/backend/src/utils/accessControl.ts b/backend/src/utils/accessControl.ts
index 725607ff..1a39d921 100644
--- a/backend/src/utils/accessControl.ts
+++ b/backend/src/utils/accessControl.ts
@@ -130,6 +130,34 @@ export async function canAccessCustomer(
   return true;
 }
 
+/**
+ * Liefert die Liste aller Customer-IDs, auf die ein Portal-User aktuell
+ * Zugriff hat: eigene + vertretene MIT aktiver Vollmacht (Live-Check via
+ * `authorizationService.hasAuthorization`). Für Nicht-Portal-User wird
+ * `null` zurückgegeben (= kein Filter, alle Kunden erlaubt).
+ *
+ * Diese Funktion fängt einen wiederkehrenden Pentest-Befund ab: ohne den
+ * Live-Vollmacht-Check hätte ein Portal-User mit widerrufener Vollmacht
+ * weiterhin Zugriff auf die Daten des vertretenen Kunden, nur weil seine
+ * `representedCustomerIds` im JWT noch drin sind (Token kann bis zu
+ * 15min alt sein).
+ */
+export async function getPortalAllowedCustomerIds(
+  req: AuthRequest,
+): Promise<number[] | null> {
+  if (!req.user?.isCustomerPortal || !req.user.customerId) return null;
+  const allowed: number[] = [req.user.customerId];
+  const represented: number[] = (req.user as any).representedCustomerIds || [];
+  for (const repCustId of represented) {
+    const hasAuth = await authorizationService.hasAuthorization(
+      repCustId,
+      req.user.customerId,
+    );
+    if (hasAuth) allowed.push(repCustId);
+  }
+  return allowed;
+}
+
 /**
  * Generische Zugriffsprüfung: Ressource → customerId → canAccessCustomer.
  */
diff --git a/docs/todo.md b/docs/todo.md
index 5966c4c9..87d9fb29 100644
--- a/docs/todo.md
+++ b/docs/todo.md
@@ -97,6 +97,67 @@ isolierte Instanz (keine Multi-Tenancy im Code), Provisioning + Abrechnung
 
 ## ✅ Erledigt
 
+- [x] **🚨 Pentest Runde 6 – Sammelfix + Strukturelles Audit (8 Findings + Audit-Sweep)**
+  - **KRITISCH-01 `GET /emails/:id/thread`**: kein Owner-Check →
+    Portal-Kunde konnte alle Mail-Threads durchsuchen. Fix:
+    `canAccessCachedEmail` im Controller.
+  - **KRITISCH-02 `GET /customers/:customerId/representatives/search`**:
+    kein `canAccessCustomer` auf den Pfad → DSGVO-GAU, Portal-Kunde
+    konnte mit Buchstaben-Brute-Force die komplette Kunden-DB
+    auslesen. Fix eingefügt.
+  - **HOCH-01 `GET /birthdays/upcoming`**: kein Portal-Filter → Name,
+    E-Mail, Telefon, Geburtsdatum aller Kunden lesbar. Fix:
+    `isCustomerPortal` → 403.
+  - **HOCH-02 `*/contracts/:contractId/history`**: kein Owner-Check
+    auf GET/POST/PUT/DELETE. Fix: `canAccessContract` in allen vier
+    History-Handlern.
+  - **HOCH-03 Mailbox-Endpoints**: `mailbox-accounts`, `unread-count`,
+    `contracts/:id/emails/folder-counts` ohne Check. Fix:
+    `canAccessCustomer` bzw. `canAccessContract` in allen drei.
+  - **HOCH-04 Live-Vollmacht-Check in Tasks**: `getTasks`,
+    `createSupportTicket`, `createCustomerReply`, `getAllTasks`,
+    `getTaskStats` prüften nur `representedCustomerIds.includes(...)`
+    aus dem JWT – widerrufene Vollmachten hatten weiter Zugriff
+    (JWT lebt bis zu 15min nach Widerruf). Neuer Helper
+    `getPortalAllowedCustomerIds()` in `accessControl.ts` ruft
+    `hasAuthorization()` live ab. Auch `updateCustomerConsent`
+    (GDPR) auf diesen Pfad umgestellt.
+  - **MITTEL-01 `confirmPasswordReset` Klartext-Speicherung**:
+    Self-Service-Reset speicherte `portalPasswordEncrypted = encrypt(pw)`.
+    Klartext-Speicherung ist nur für Admin-OTPs sinnvoll. Fix:
+    Field auf null, zusätzlich `portalPasswordMustChange = false`.
+  - **MITTEL-02 Pagination-Total leakt globale Kunden-Anzahl**:
+    `GET /customers` gab `total: 4271` auch wenn Portal-User nur
+    1 Kunde sah. Fix: `customer.service.ts` erweitert um
+    `allowedIds`-Filter, der direkt in der DB-Query landet → die
+    pagination zählt nur über erlaubte IDs.
+  - **Strukturelles Audit-Sweep** (Sub-CRUD + Email-Operationen):
+    Folgende Handler bekamen jetzt erstmals einen `canAccess*`-
+    Check, defense in depth gegen falsch vergebene Rollen:
+    `markAsRead`, `toggleStar`, `assignToContract`,
+    `unassignFromContract`, `deleteEmail`, `getTrashEmails`,
+    `getTrashCount`, `restoreEmail`, `permanentDeleteEmail`,
+    `getAttachmentTargets`, `saveAttachmentTo`, `saveEmailAsPdf`,
+    `saveEmailAsInvoice`, `saveAttachmentAsInvoice`,
+    `saveAttachmentAsContractDocument`, `createFollowUp`,
+    `createRenewal`, `snoozeContract`, `removeContractMeter`,
+    `updateAddress`, `deleteAddress`, `updateBankCard`,
+    `deleteBankCard`, `updateDocument`, `deleteDocument`,
+    `updateMeter`, `deleteMeter`, `addMeterReading`,
+    `updateMeterReading`, `deleteMeterReading`,
+    `markReadingTransferred`, `addRepresentative`,
+    `removeRepresentative`.
+  - **Live-verifiziert** (Portal-User Customer 3 auf fremde IDs):
+    `customers/1/representatives/search` → 403,
+    `birthdays/upcoming` → 403 (Admin → 200),
+    `emails/21/thread` → 403,
+    `customers/2/mailbox-accounts` → 403,
+    `emails/unread-count?customerId=2` → 403,
+    `contracts/8/{history,folder-counts,follow-up,renewal,snooze}` → 403,
+    eigene `customers/3` → 200,
+    pagination.total für Portal = 1 (statt 3),
+    Customer 1 mit widerrufener Vollmacht → 0 fremde Verträge.
+
 - [x] **🚨 Pentest Runde 5 – KRITISCH: change-initial-portal-password ohne Pflicht-Check**
   - **Realer Angriff**: Jeder Portal-User konnte jederzeit mit
     seinem eingeloggten Token `POST /api/auth/change-initial-portal-