diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3b615fe..9a96dba 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,27 @@
 
 All notable changes to this project are documented in this file.
 
+## [1.123.2] - 2026-09-12
+
+Erste drei Punkte aus dem TODO-Block L (Sicherheitsdurchgang vom 12.09.) — sichere, in
+sich abgeschlossene Änderungen ohne Datenmodell-Migration.
+
+### Security
+- **Kein automatischer `db push --accept-data-loss`-Fallback mehr in
+  `scripts/update-app.sh`.** Eine fehlgeschlagene `prisma migrate deploy` bricht das
+  Deployment jetzt sauber ab statt unbeaufsichtigt das Schema zu überschreiben — genau
+  dieser Fallback ist am 11.09. beim Boot-Lauf tatsächlich ausgelöst worden.
+- **14 API-Routen gaben rohe Fehlermeldungen (`error.message`) direkt an den Client
+  zurück** (Kalender-Connect/-Sync, Task-Import/-Sync, Someday-Listen, Datenimport). Neuer
+  Helper `src/lib/api-error.ts` (`safeErrorMessage`): generische Meldung in Produktion,
+  echte Meldung nur noch lokal beim Entwickeln. Volles Logging bleibt unverändert in
+  `console.error`.
+- SMTP-Zertifikatsprüfung wieder aktiv: `tls: { rejectUnauthorized: false }` in
+  `src/lib/email.ts` entfernt — stand unbegründet seit dem allerersten Commit der Datei und
+  öffnete Tür für Man-in-the-Middle auf Passwort-Reset-/Verifizierungs-Mails.
+
+Verifiziert: Typecheck, Lint, 79 Unit-Tests, Produktions-Build alle grün.
+
 ## [1.123.1] - 2026-09-12
 
 ### Fixed
diff --git a/package.json b/package.json
index 2db0826..8b1f8c9 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "my-weekly-todo-list",
-  "version": "1.123.1",
+  "version": "1.123.2",
   "description": "A web-based weekly task management application that organizes to-dos and calendar events in a single, intuitive weekly view",
   "main": "index.js",
   "scripts": {
diff --git a/scripts/update-app.sh b/scripts/update-app.sh
index 589ae43..72ecaa6 100755
--- a/scripts/update-app.sh
+++ b/scripts/update-app.sh
@@ -104,11 +104,15 @@ main() {
         npm ci
     fi
 
+    # Kein automatischer db-push-Fallback mehr: "--accept-data-loss" darf niemand
+    # unbeaufsichtigt aus einem Deploy-Skript heraus zustimmen. Das ist am 11.09. beim
+    # Boot-Lauf tatsaechlich ausgeloest worden ("migrate deploy failed, falling back to
+    # db push..."), ohne dass irgendjemand das gesehen oder bestaetigt haette. Ein
+    # fehlgeschlagenes Migrate bricht das Update jetzt sauber ab -- die laufende App bleibt
+    # unveraendert, exakt wie bei einem fehlgeschlagenen Build. Migrationsfehler muessen von
+    # Hand untersucht werden, nicht automatisch ueberschrieben.
     log "--- Updating database schema (safe migrate) ---"
-    npx prisma migrate deploy || {
-        log "migrate deploy failed, falling back to db push..."
-        npx prisma db push --accept-data-loss
-    }
+    npx prisma migrate deploy
 
     log "--- Regenerating Prisma client ---"
     npx prisma generate
diff --git a/src/app/api/calendar/apple/connect/route.ts b/src/app/api/calendar/apple/connect/route.ts
index 0486d89..9f40328 100644
--- a/src/app/api/calendar/apple/connect/route.ts
+++ b/src/app/api/calendar/apple/connect/route.ts
@@ -1,4 +1,5 @@
 import { NextResponse } from 'next/server';
+import { safeErrorMessage } from '@/lib/api-error';
 import { validateCredentials } from '@/lib/apple-calendar';
 import { CalendarConnection } from '@/lib/calendar-sync';
 import { getServerSession } from 'next-auth';
@@ -82,7 +83,7 @@ export async function POST(req: Request) {
     } catch (error: any) {
         console.error('Error connecting Apple Calendar:', error);
         return NextResponse.json(
-            { error: error.message || 'Failed to connect Apple Calendar' },
+            { error: safeErrorMessage(error, 'Failed to connect Apple Calendar') },
             { status: 500 }
         );
     }
diff --git a/src/app/api/calendar/apple/sync/route.ts b/src/app/api/calendar/apple/sync/route.ts
index da39833..e343336 100644
--- a/src/app/api/calendar/apple/sync/route.ts
+++ b/src/app/api/calendar/apple/sync/route.ts
@@ -2,6 +2,7 @@ import { NextResponse } from 'next/server';
 import { getServerSession } from 'next-auth';
 import { getUpcomingEvents } from '@/lib/apple-calendar';
 import { authOptions } from "@/lib/auth";
+import { safeErrorMessage } from '@/lib/api-error';
 
 export async function POST(req: Request) {
     try {
@@ -36,7 +37,7 @@ export async function POST(req: Request) {
     } catch (error: any) {
         console.error('Error syncing Apple Calendar:', error);
         return NextResponse.json(
-            { error: error.message || 'Failed to sync Apple Calendar' },
+            { error: safeErrorMessage(error, 'Failed to sync Apple Calendar') },
             { status: 500 }
         );
     }
diff --git a/src/app/api/calendar/events/route.ts b/src/app/api/calendar/events/route.ts
index 5601822..8272697 100644
--- a/src/app/api/calendar/events/route.ts
+++ b/src/app/api/calendar/events/route.ts
@@ -1,4 +1,5 @@
 import { NextRequest, NextResponse } from 'next/server';
+import { safeErrorMessage } from '@/lib/api-error';
 import { getServerSession } from 'next-auth';
 import { authOptions } from "@/lib/auth";
 import { prisma } from '@/lib/prisma';
@@ -98,7 +99,7 @@ export async function POST(request: NextRequest) {
         return NextResponse.json({ event });
     } catch (error: any) {
         console.error('Error creating event:', error);
-        return NextResponse.json({ error: error.message || 'Failed to create event' }, { status: 500 });
+        return NextResponse.json({ error: safeErrorMessage(error, 'Failed to create event') }, { status: 500 });
     }
 }
 
@@ -195,7 +196,7 @@ export async function PATCH(request: NextRequest) {
         return NextResponse.json({ event });
     } catch (error: any) {
         console.error('Error updating event:', error);
-        return NextResponse.json({ error: error.message || 'Failed to update event' }, { status: 500 });
+        return NextResponse.json({ error: safeErrorMessage(error, 'Failed to update event') }, { status: 500 });
     }
 }
 
@@ -241,6 +242,6 @@ export async function DELETE(request: NextRequest) {
         return NextResponse.json({ success: true });
     } catch (error: any) {
         console.error('Error deleting event:', error);
-        return NextResponse.json({ error: error.message || 'Failed to delete event' }, { status: 500 });
+        return NextResponse.json({ error: safeErrorMessage(error, 'Failed to delete event') }, { status: 500 });
     }
 }
diff --git a/src/app/api/calendar/sync/route.ts b/src/app/api/calendar/sync/route.ts
index 9661b7e..a722bec 100644
--- a/src/app/api/calendar/sync/route.ts
+++ b/src/app/api/calendar/sync/route.ts
@@ -5,6 +5,7 @@ import { authOptions } from "@/lib/auth";
 import { prisma } from '@/lib/prisma';
 import { readCachedEvents, isCacheStale, refreshConnectionCache, RefreshableConnection } from '@/lib/calendar-cache';
 import { runSyncRules } from '@/lib/calendar-cross-sync';
+import { safeErrorMessage } from '@/lib/api-error';
 
 export async function POST(request: NextRequest) {
     try {
@@ -108,7 +109,7 @@ export async function POST(request: NextRequest) {
         console.error('[CALENDAR SYNC] Sync request failed:', error);
         return NextResponse.json({
             error: 'Sync failed',
-            details: error instanceof Error ? error.message : 'Unknown error'
+            details: safeErrorMessage(error, 'Unknown error')
         }, { status: 500 });
     }
 }
diff --git a/src/app/api/calendar/synology/connect/route.ts b/src/app/api/calendar/synology/connect/route.ts
index 986a565..7bb139d 100644
--- a/src/app/api/calendar/synology/connect/route.ts
+++ b/src/app/api/calendar/synology/connect/route.ts
@@ -3,6 +3,7 @@ import { validateCredentials } from '@/lib/synology-calendar';
 import { getServerSession } from 'next-auth';
 import { authOptions } from "@/lib/auth";
 import { prisma } from '@/lib/prisma';
+import { safeErrorMessage } from '@/lib/api-error';
 
 export async function POST(req: Request) {
     try {
@@ -80,7 +81,7 @@ export async function POST(req: Request) {
     } catch (error: any) {
         console.error('Error connecting Synology Calendar:', error);
         return NextResponse.json(
-            { error: error.message || 'Failed to connect Synology Calendar' },
+            { error: safeErrorMessage(error, 'Failed to connect Synology Calendar') },
             { status: 500 }
         );
     }
diff --git a/src/app/api/someday-lists/external/route.ts b/src/app/api/someday-lists/external/route.ts
index 469e3de..2a094aa 100644
--- a/src/app/api/someday-lists/external/route.ts
+++ b/src/app/api/someday-lists/external/route.ts
@@ -4,6 +4,7 @@ import { getServerSession } from 'next-auth';
 import { authOptions } from "@/lib/auth";
 import { prisma } from '@/lib/prisma';
 import { createGoogleClient, createGoogleTaskList } from '@/lib/google-tasks';
+import { safeErrorMessage } from '@/lib/api-error';
 import { createMsTodoList } from '@/lib/microsoft-todo';
 import { getOutlookAccessToken } from '@/lib/outlook-token';
 import { createAppleReminderList } from '@/lib/apple-reminders';
@@ -104,7 +105,7 @@ export async function POST(req: NextRequest) {
     } catch (error: any) {
         console.error('Error creating external someday list:', error);
         return NextResponse.json(
-            { error: error.message || 'Failed to create list' },
+            { error: safeErrorMessage(error, 'Failed to create list') },
             { status: 500 }
         );
     }
diff --git a/src/app/api/tasks/import/route.ts b/src/app/api/tasks/import/route.ts
index e389ed8..44181f9 100644
--- a/src/app/api/tasks/import/route.ts
+++ b/src/app/api/tasks/import/route.ts
@@ -4,6 +4,7 @@ import { getServerSession } from 'next-auth';
 import { authOptions } from "@/lib/auth";
 import { prisma } from '@/lib/prisma';
 import { createGoogleClient, fetchGoogleTasks, fetchGoogleTaskLists } from '@/lib/google-tasks';
+import { safeErrorMessage } from '@/lib/api-error';
 import { fetchMsTodoLists, fetchMsTodoTasks, isMsTodoTaskCompleted, fetchMsChecklistItems } from '@/lib/microsoft-todo';
 import { getOutlookAccessToken } from '@/lib/outlook-token';
 
@@ -343,7 +344,7 @@ export async function POST(req: NextRequest) {
 
     } catch (error: unknown) {
         console.error('Import error:', error);
-        const message = error instanceof Error ? error.message : 'Import failed';
+        const message = safeErrorMessage(error, 'Import failed');
         return NextResponse.json({ error: message }, { status: 500 });
     }
 }
diff --git a/src/app/api/tasks/lists/route.ts b/src/app/api/tasks/lists/route.ts
index 43eb457..c5c298b 100644
--- a/src/app/api/tasks/lists/route.ts
+++ b/src/app/api/tasks/lists/route.ts
@@ -4,6 +4,7 @@ import { authOptions } from "@/lib/auth";
 import { prisma } from '@/lib/prisma';
 import { createGoogleClient, fetchGoogleTaskLists } from '@/lib/google-tasks';
 import { fetchMsTodoLists } from '@/lib/microsoft-todo';
+import { safeErrorMessage } from '@/lib/api-error';
 import { getOutlookAccessToken } from '@/lib/outlook-token';
 
 export const dynamic = 'force-dynamic';
@@ -83,7 +84,7 @@ export async function GET(req: NextRequest) {
 
     } catch (error: unknown) {
         console.error('Fetch lists error:', error);
-        const message = error instanceof Error ? error.message : 'Failed to fetch lists';
+        const message = safeErrorMessage(error, 'Failed to fetch lists');
         return NextResponse.json({ error: message }, { status: 500 });
     }
 }
diff --git a/src/app/api/tasks/sync/route.ts b/src/app/api/tasks/sync/route.ts
index 3a3bfac..3236d68 100644
--- a/src/app/api/tasks/sync/route.ts
+++ b/src/app/api/tasks/sync/route.ts
@@ -4,6 +4,7 @@ import { authOptions } from "@/lib/auth";
 import { prisma } from '@/lib/prisma';
 import { createGoogleClient, createGoogleTask, updateGoogleTaskStatus, updateGoogleTask, deleteGoogleTask, fetchGoogleTasksForSync, GoogleTask } from '@/lib/google-tasks';
 import { fetchMsTodoTasksForSync, fetchMsTodoTasksDelta, updateMsTodoTask, deleteMsTodoTask, createMsTodoTask, isMsTodoTaskCompleted } from '@/lib/microsoft-todo';
+import { safeErrorMessage } from '@/lib/api-error';
 import { getOutlookAccessToken } from '@/lib/outlook-token';
 
 // GET - Pull changes from Google Tasks into local DB
@@ -567,7 +568,7 @@ export async function GET(req: NextRequest) {
 
     } catch (error: unknown) {
         console.error('Pull sync error:', error);
-        const message = error instanceof Error ? error.message : 'Pull sync failed';
+        const message = safeErrorMessage(error, 'Pull sync failed');
         return NextResponse.json({ error: message }, { status: 500 });
     }
 }
@@ -706,7 +707,7 @@ export async function PATCH(req: NextRequest) {
 
     } catch (error: unknown) {
         console.error('Sync error:', error);
-        const message = error instanceof Error ? error.message : 'Sync failed';
+        const message = safeErrorMessage(error, 'Sync failed');
         return NextResponse.json({ error: message }, { status: 500 });
     }
 }
@@ -839,7 +840,7 @@ export async function POST(req: NextRequest) {
 
     } catch (error: unknown) {
         console.error('Task creation sync error:', error);
-        const message = error instanceof Error ? error.message : 'Task creation sync failed';
+        const message = safeErrorMessage(error, 'Task creation sync failed');
         return NextResponse.json({ error: message }, { status: 500 });
     }
 }
diff --git a/src/app/api/user/import-data/route.ts b/src/app/api/user/import-data/route.ts
index 4d2a572..440c881 100644
--- a/src/app/api/user/import-data/route.ts
+++ b/src/app/api/user/import-data/route.ts
@@ -2,6 +2,7 @@ import { NextResponse } from 'next/server';
 import { getServerSession } from 'next-auth';
 import { authOptions } from "@/lib/auth";
 import { prisma } from '@/lib/prisma';
+import { safeErrorMessage } from '@/lib/api-error';
 
 interface ImportTask {
     id?: string;
@@ -262,7 +263,7 @@ export async function POST(request: Request) {
         if (error instanceof SyntaxError) {
             message = 'Invalid JSON file';
         } else if (error instanceof Error) {
-            message = `Import failed: ${error.message}`;
+            message = safeErrorMessage(error, 'Import failed');
         }
         return NextResponse.json({ error: message }, { status: 500 });
     }
diff --git a/src/lib/api-error.ts b/src/lib/api-error.ts
new file mode 100644
index 0000000..6573807
--- /dev/null
+++ b/src/lib/api-error.ts
@@ -0,0 +1,16 @@
+/**
+ * Sichere Fehlermeldung fuer API-Antworten.
+ *
+ * Mehrere Routen haben bislang `error.message` direkt in die JSON-Antwort geschrieben --
+ * das kann Datenbankfehler, Dateipfade oder Provider-interne Details an den Client (und
+ * damit an jeden, der die API abfragt) durchreichen. In der Produktion gibt es deshalb nur
+ * noch die generische Fallback-Meldung; lokal beim Entwickeln weiterhin die echte Meldung,
+ * damit Fehlersuche nicht erschwert wird. Das vollstaendige Loggen des Fehlers bleibt
+ * Aufgabe der aufrufenden Stelle (meist schon vorhandenes `console.error` direkt davor).
+ */
+export function safeErrorMessage(error: unknown, fallback: string): string {
+  if (process.env.NODE_ENV !== 'production' && error instanceof Error && error.message) {
+    return error.message;
+  }
+  return fallback;
+}
diff --git a/src/lib/email.ts b/src/lib/email.ts
index 071262f..861e9b5 100644
--- a/src/lib/email.ts
+++ b/src/lib/email.ts
@@ -20,7 +20,11 @@ function getTransporter() {
       port,
       secure,
       auth: { user, pass },
-      tls: { rejectUnauthorized: false },
+      // Kein rejectUnauthorized: false mehr -- das schaltete die Zertifikatspruefung fuer
+      // die SMTP-Verbindung komplett ab (Tuer fuer MITM auf Passwort-Reset-/Verifizierungs-
+      // Mails) und war seit dem allerersten Commit unbegruendet gesetzt. Der produktiv
+      // konfigurierte Host (Kasserver) hat ein gueltiges Zertifikat; keine Notwendigkeit,
+      // die Pruefung abzuschalten.
     });
   }
   return _transporter;