From 4ae5b2f502f35658c59c90e0a2082a1d9cc44dbb Mon Sep 17 00:00:00 2001
From: med8bra <med8bra@gmail.com>
Date: Fri, 23 Feb 2024 02:03:46 +0100
Subject: [PATCH] fix(security-middleware): fix config merging with defaults

---
 .../middlewares/__tests__/security.test.ts    | 65 +++++++++++++++++++
 .../core/strapi/src/middlewares/security.ts   | 14 +++-
 2 files changed, 76 insertions(+), 3 deletions(-)
 create mode 100644 packages/core/strapi/src/middlewares/__tests__/security.test.ts

diff --git a/packages/core/strapi/src/middlewares/__tests__/security.test.ts b/packages/core/strapi/src/middlewares/__tests__/security.test.ts
new file mode 100644
index 0000000000..a242c4de9b
--- /dev/null
+++ b/packages/core/strapi/src/middlewares/__tests__/security.test.ts
@@ -0,0 +1,65 @@
+import Koa from 'koa';
+import request from 'supertest';
+import { security } from '../security';
+
+const parseCspHeader = (csp: string) =>
+  Object.fromEntries(
+    csp
+      .split(';')
+      .map((directive) => directive.split(' '))
+      .map(([k, ...v]) => [k, v])
+  );
+
+describe('Security middleware', () => {
+  describe('Content security policy', () => {
+    // GIVEN
+    const app = new Koa();
+    const securityMiddleware = security(
+      {
+        contentSecurityPolicy: {
+          useDefaults: true,
+          directives: {
+            'script-src': ["'self'", 'https://cdn.custom.com'],
+            upgradeInsecureRequests: null,
+          },
+        },
+      },
+      {
+        strapi: {
+          plugin: () => null,
+        } as any,
+      }
+    )!;
+
+    // WHEN
+    app.use(securityMiddleware);
+    const agent = request.agent(app.callback());
+
+    // THEN
+    it.each(['/', '/admin', '/api'])(
+      'includes user custom CSP directives in GET %s response',
+      async (path) => {
+        await agent.get(path).expect((req) => {
+          const csp = parseCspHeader(req.header['content-security-policy']);
+          expect(csp['script-src']).toContain('https://cdn.custom.com');
+        });
+      }
+    );
+    it('includes required default CSP directives in GET /admin response', async () => {
+      await agent.get('/admin').expect((req) => {
+        const csp = parseCspHeader(req.header['content-security-policy']);
+        expect(csp['script-src']).toContain("'unsafe-inline'");
+        expect(csp['connect-src']).toContain('ws:');
+      });
+    });
+    it('includes required default CSP directives in GET /documentation response', async () => {
+      await agent.get('/documentation').expect((req) => {
+        const csp = parseCspHeader(req.header['content-security-policy']);
+        expect(csp['script-src']).toContain("'unsafe-inline'");
+        expect(csp['script-src']).toContain('cdn.jsdelivr.net');
+        expect(csp['img-src']).toContain('strapi.io');
+        expect(csp['img-src']).toContain('cdn.jsdelivr.net');
+      });
+    });
+  });
+});
diff --git a/packages/core/strapi/src/middlewares/security.ts b/packages/core/strapi/src/middlewares/security.ts
index 13c645ac31..6c886437e0 100644
--- a/packages/core/strapi/src/middlewares/security.ts
+++ b/packages/core/strapi/src/middlewares/security.ts
@@ -1,4 +1,4 @@
-import { defaultsDeep, merge } from 'lodash/fp';
+import { defaultsDeep, mergeWith } from 'lodash/fp';
 import helmet, { KoaHelmet } from 'koa-helmet';
 
 import type { Common } from '@strapi/types';
@@ -29,6 +29,14 @@ const defaults: Config = {
   },
 };
 
+const mergeConfig = (existingConfig: Config, newConfig: Config) => {
+  return mergeWith(
+    (obj, src) => (Array.isArray(obj) && Array.isArray(src) ? obj.concat(src) : undefined),
+    existingConfig,
+    newConfig
+  );
+};
+
 export const security: Common.MiddlewareFactory<Config> =
   (config, { strapi }) =>
   (ctx, next) => {
@@ -42,7 +50,7 @@ export const security: Common.MiddlewareFactory<Config> =
     }
 
     if (ctx.method === 'GET' && specialPaths.some((str) => ctx.path.startsWith(str))) {
-      helmetConfig = merge(helmetConfig, {
+      helmetConfig = mergeConfig(helmetConfig, {
         contentSecurityPolicy: {
           directives: {
             'script-src': ["'self'", "'unsafe-inline'", 'cdn.jsdelivr.net'],
@@ -53,7 +61,7 @@ export const security: Common.MiddlewareFactory<Config> =
     }
 
     if (ctx.method === 'GET' && ['/admin'].some((str) => ctx.path.startsWith(str))) {
-      helmetConfig = merge(helmetConfig, {
+      helmetConfig = mergeConfig(helmetConfig, {
         contentSecurityPolicy: {
           directives: {
             'script-src': ["'self'", "'unsafe-inline'"],