feat: add helmet middleware for security and implement Content Security Policy in Next.js configuration

backend/package.json

@@ -30,7 +30,8 @@
     "rxjs": "^7.8.1",
     "sharp": "^0.33.5",
     "tesseract.js": "^6.0.1",
-    "uuid": "^11.1.0"
+    "uuid": "^11.1.0",
+    "helmet": "^8.0.0"
   },
   "devDependencies": {
     "@nestjs/cli": "^10.3.0",

backend/src/main.ts

@@ -2,10 +2,31 @@ import { ValidationPipe } from '@nestjs/common';
 import { NestFactory } from '@nestjs/core';
 import { AppModule } from './app.module';
 import { GlobalExceptionFilter } from './common/filters/global-exception.filter';
+import helmet from 'helmet';
 
 async function bootstrap() {
   const app = await NestFactory.create(AppModule);
 
+  // Helmet som säkerhetsbackup (CSP hanteras av Next.js/Caddy)
+  app.use(
+    helmet({
+      contentSecurityPolicy: false,
+      crossOriginEmbedderPolicy: true,
+      crossOriginOpenerPolicy: { policy: 'same-origin' },
+      crossOriginResourcePolicy: { policy: 'same-origin' },
+      originAgentCluster: true,
+      referrerPolicy: { policy: 'strict-origin-when-cross-origin' },
+      strictTransportSecurity: {
+        maxAge: 31536000,
+        includeSubDomains: true,
+        preload: true,
+      },
+      xContentTypeOptions: true,
+      xFrameOptions: { action: 'deny' },
+      xXssProtection: false, // Deprecated, hanteras av Caddy
+    }),
+  );
+
   app.setGlobalPrefix('api');
   
   // Registrera global exception filter

frontend/next.config.js

@@ -9,6 +9,33 @@ const nextConfig = {
       },
     ];
   },
+  async headers() {
+    const csp = [
+      "default-src 'self'",
+      "script-src 'self' 'unsafe-eval' 'unsafe-inline'",
+      "style-src 'self' 'unsafe-inline' https://fonts.googleapis.com",
+      "img-src 'self' data: https:",
+      "font-src 'self' https://fonts.gstatic.com",
+      "connect-src 'self' https://api.mistral.ai",
+      "frame-src 'none'",
+      "object-src 'none'",
+      "base-uri 'self'",
+      "form-action 'self'",
+      "upgrade-insecure-requests",
+    ].join('; ');
+
+    return [
+      {
+        source: '/:path*',
+        headers: [
+          {
+            key: 'Content-Security-Policy',
+            value: csp,
+          },
+        ],
+      },
+    ];
+  },
 };
 
 module.exports = nextConfig;