diff --git a/backend/src/controllers/cachedEmail.controller.ts b/backend/src/controllers/cachedEmail.controller.ts
index b57eb130..8a0e4446 100644
--- a/backend/src/controllers/cachedEmail.controller.ts
+++ b/backend/src/controllers/cachedEmail.controller.ts
@@ -8,7 +8,7 @@ import { sendEmail, SmtpCredentials, SendEmailParams, EmailAttachment } from '..
 import { fetchAttachment, appendToSent, ImapCredentials } from '../services/imapService.js';
 import { getImapSmtpSettings } from '../services/emailProvider/emailProviderService.js';
 import { decrypt } from '../utils/encryption.js';
-import { sanitizeNotes, stripHtml, validateContractDocumentType } from '../utils/sanitize.js';
+import { sanitizeNotes, stripHtml, validateContractDocumentType, validateOptionalIsoDate } from '../utils/sanitize.js';
 import { logChange } from '../services/audit.service.js';
 import { ApiResponse, AuthRequest } from '../types/index.js';
 import { getCustomerTargets, getContractTargets, getIdentityDocumentTargets, getBankCardTargets, documentTargets } from '../config/documentTargets.config.js';
@@ -1836,6 +1836,15 @@ export async function saveEmailAsContractDocument(req: AuthRequest, res: Respons
       return;
     }
 
+    // Pentest 62.7: deliveryDate früh validieren, bevor wir Dateien schreiben.
+    let deliveryDate: string | null;
+    try {
+      deliveryDate = validateOptionalIsoDate(req.body?.deliveryDate, 'deliveryDate');
+    } catch (err) {
+      res.status(400).json({ success: false, error: err instanceof Error ? err.message : 'Ungültiges Lieferdatum' } as ApiResponse);
+      return;
+    }
+
     const email = await cachedEmailService.getCachedEmailById(emailId);
     if (!email) {
       res.status(404).json({ success: false, error: 'E-Mail nicht gefunden' } as ApiResponse);
@@ -1898,8 +1907,8 @@ export async function saveEmailAsContractDocument(req: AuthRequest, res: Respons
       });
     });
 
-    // Falls Lieferbestätigung: DRAFT → ACTIVE + startDate setzen falls leer
-    const deliveryDate = typeof req.body?.deliveryDate === 'string' ? req.body.deliveryDate : null;
+    // Falls Lieferbestätigung: DRAFT → ACTIVE + startDate setzen falls leer.
+    // deliveryDate wurde oben schon validiert (Pentest 62.7).
     await maybeActivateOnDeliveryConfirmation(contract.id, validatedType, req, deliveryDate);
 
     res.json({ success: true, data: doc } as ApiResponse);
@@ -2096,6 +2105,15 @@ export async function saveAttachmentAsContractDocument(req: AuthRequest, res: Re
       return;
     }
 
+    // Pentest 62.7: deliveryDate früh validieren, bevor wir Dateien schreiben.
+    let deliveryDate: string | null;
+    try {
+      deliveryDate = validateOptionalIsoDate(req.body?.deliveryDate, 'deliveryDate');
+    } catch (err) {
+      res.status(400).json({ success: false, error: err instanceof Error ? err.message : 'Ungültiges Lieferdatum' } as ApiResponse);
+      return;
+    }
+
     const email = await cachedEmailService.getCachedEmailById(emailId);
     if (!email) {
       res.status(404).json({ success: false, error: 'E-Mail nicht gefunden' } as ApiResponse);
@@ -2201,8 +2219,8 @@ export async function saveAttachmentAsContractDocument(req: AuthRequest, res: Re
       });
     });
 
-    // Falls Lieferbestätigung: DRAFT → ACTIVE + startDate setzen falls leer
-    const deliveryDate = typeof req.body?.deliveryDate === 'string' ? req.body.deliveryDate : null;
+    // Falls Lieferbestätigung: DRAFT → ACTIVE + startDate setzen falls leer.
+    // deliveryDate wurde oben schon validiert (Pentest 62.7).
     await maybeActivateOnDeliveryConfirmation(contract.id, validatedType, req, deliveryDate);
 
     res.json({ success: true, data: doc } as ApiResponse);
diff --git a/backend/src/controllers/contract.controller.ts b/backend/src/controllers/contract.controller.ts
index 71aab25e..6cb509f2 100644
--- a/backend/src/controllers/contract.controller.ts
+++ b/backend/src/controllers/contract.controller.ts
@@ -8,7 +8,7 @@ import * as authorizationService from '../services/authorization.service.js';
 import { recordPredecessorFinalReading } from '../services/customer.service.js';
 import { ApiResponse, AuthRequest } from '../types/index.js';
 import { logChange } from '../services/audit.service.js';
-import { sanitizeContract, sanitizeContractStrict, sanitizeContracts, sanitizeContractsStrict, stripHtml, sanitizeNotes, validateContractDocumentType } from '../utils/sanitize.js';
+import { sanitizeContract, sanitizeContractStrict, sanitizeContracts, sanitizeContractsStrict, stripHtml, sanitizeNotes, validateContractDocumentType, validateOptionalIsoDate } from '../utils/sanitize.js';
 import { canAccessContract } from '../utils/accessControl.js';
 import { maybeActivateOnDeliveryConfirmation, withContractDocumentLock } from '../services/contractStatusScheduler.service.js';
 
@@ -722,7 +722,7 @@ export async function uploadContractDocument(req: AuthRequest, res: Response): P
   try {
     const contractId = parseInt(req.params.id);
     if (!(await canAccessContract(req, res, contractId))) return;
-    const { documentType, notes, deliveryDate } = req.body;
+    const { documentType, notes } = req.body;
 
     if (!req.file) {
       res.status(400).json({ success: false, error: 'Keine Datei hochgeladen' } as ApiResponse);
@@ -734,6 +734,16 @@ export async function uploadContractDocument(req: AuthRequest, res: Response): P
       return;
     }
 
+    // Pentest 62.7: deliveryDate validieren (ISO-8601 oder null).
+    let deliveryDate: string | null;
+    try {
+      deliveryDate = validateOptionalIsoDate(req.body?.deliveryDate, 'deliveryDate');
+    } catch (err) {
+      try { fs.unlinkSync(req.file.path); } catch { /* ignore */ }
+      res.status(400).json({ success: false, error: err instanceof Error ? err.message : 'Ungültiges Lieferdatum' } as ApiResponse);
+      return;
+    }
+
     const documentPath = `/uploads/contract-documents/${req.file.filename}`;
     // Pentest 58.1: Whitelist-Validierung statt nur stripHtml. Multer hat
     // die Datei schon geschrieben – bei Reject räumen wir sie wieder weg.
diff --git a/backend/src/routes/upload.routes.ts b/backend/src/routes/upload.routes.ts
index 452746c5..1cf973a8 100644
--- a/backend/src/routes/upload.routes.ts
+++ b/backend/src/routes/upload.routes.ts
@@ -12,6 +12,7 @@ import {
   canAccessBankCard,
   canAccessIdentityDocument,
 } from '../utils/accessControl.js';
+import { validateOptionalIsoDate } from '../utils/sanitize.js';
 
 // Pentest 56.1 (HIGH, 2026-06-01): Upload-Endpoints prüften nur die
 // Permission, nicht ob die Ziel-Resource zum Caller passt. Helper-Funktion
@@ -738,11 +739,18 @@ async function handleContractDocumentUpload(
       const dateField = fieldName === 'cancellationConfirmationPath'
         ? 'cancellationConfirmationDate'
         : 'cancellationConfirmationOptionsDate';
-      const provided = typeof req.body?.confirmationDate === 'string' ? req.body.confirmationDate : null;
+      // Pentest 62.7: confirmationDate gegen ISO-8601 validieren.
+      let provided: string | null;
+      try {
+        provided = validateOptionalIsoDate(req.body?.confirmationDate, 'confirmationDate');
+      } catch (err) {
+        cleanupFile(req.file?.path);
+        res.status(400).json({ success: false, error: err instanceof Error ? err.message : 'Ungültiges Bestätigungsdatum' });
+        return;
+      }
       let target: Date | null = null;
       if (provided) {
-        const parsed = new Date(provided);
-        if (!isNaN(parsed.getTime())) target = parsed;
+        target = new Date(provided);
       }
       if (target) {
         updateData[dateField] = target;
diff --git a/backend/src/utils/sanitize.ts b/backend/src/utils/sanitize.ts
index a458b79f..768608a7 100644
--- a/backend/src/utils/sanitize.ts
+++ b/backend/src/utils/sanitize.ts
@@ -246,6 +246,33 @@ export function sanitizePhoneField(raw: unknown, fieldLabel: string): string | u
   return trimmed;
 }
 
+// Pentest 62.7 (LOW, 2026-06-02): deliveryDate/confirmationDate-Felder
+// liefen ungeprüft in maybeActivateOnDeliveryConfirmation. XSS-Payloads
+// gingen mit 200 durch, weil das ungültige Datum nur silent als null
+// behandelt wurde. Impact gering, aber API-Hygiene: ungültige Eingabe
+// soll 400 zurückgeben, nicht 200.
+//
+// Akzeptiert: ISO-8601-Datum (YYYY-MM-DD) und Datum+Zeit (mit oder ohne
+// Zeitzone). Whitespace wird getrimmt. null / leerer String / undefined
+// sind OK – der Aufrufer behandelt das als "Datum nicht gesetzt".
+const ISO_DATE_REGEX = /^\d{4}-\d{2}-\d{2}(T\d{2}:\d{2}(:\d{2}(\.\d+)?)?(Z|[+-]\d{2}:?\d{2})?)?$/;
+export function validateOptionalIsoDate(raw: unknown, fieldLabel: string): string | null {
+  if (raw == null) return null;
+  if (typeof raw !== 'string') {
+    throw new Error(`${fieldLabel} muss ein Datums-String (YYYY-MM-DD) sein.`);
+  }
+  const trimmed = raw.trim();
+  if (trimmed === '') return null;
+  if (!ISO_DATE_REGEX.test(trimmed)) {
+    throw new Error(`${fieldLabel} muss ISO-8601-Format haben (YYYY-MM-DD oder YYYY-MM-DDTHH:MM:SS).`);
+  }
+  const parsed = new Date(trimmed);
+  if (isNaN(parsed.getTime())) {
+    throw new Error(`${fieldLabel} ist kein gültiges Datum.`);
+  }
+  return trimmed;
+}
+
 const NOTES_DEFAULT_MAX = 2000;
 export function sanitizeNotes(raw: unknown, maxLength: number = NOTES_DEFAULT_MAX): string | null {
   if (raw == null) return null;