phpMyFAQ is an open source FAQ web application. Prior to version 4.1.1, the MediaBrowserController::index() method handles file deletion for the media browser. When the fileRemove action is triggered, the user-supplied name parameter is concatenated with the base upload directory path without any path traversal validation. The FILTER_SANITIZE_SPECIAL_CHARS filter only encodes HTML special characters (&, ', ", <, >) and characters with ASCII value < 32, and does not prevent directory traversal sequences like ../. Additionally, the endpoint does not validate CSRF tokens, making it exploitable via CSRF attacks. This issue has been patched in version 4.1.1.

Affected: Packagist: phpmyfaq/phpmyfaq

### Summary The `MediaBrowserController::index()` method handles file deletion for the media browser. When the `fileRemove` action is triggered, the user-supplied `name` parameter is concatenated with the base upload directory path without any path traversal validation. The `FILTER_SANITIZE_SPECIAL_CHARS` filter only encodes HTML special characters (`&`, `'`, `"`, `<`, `>`) and characters with ASCII value < 32, and does not prevent directory traversal sequences like `../`. Additionally, the endpoint does not validate CSRF tokens, making it exploitable via CSRF attacks.

### Details

**Affected File:** `phpmyfaq/src/phpMyFAQ/Controller/Administration/Api/MediaBrowserController.php`

**Lines 43-66:** ```php #[Route(path: 'media-browser', name: 'admin.api.media.browser', methods: ['GET'])] public function index(Request $request): JsonResponse|Response { $this->userHasPermission(PermissionType::FAQ_EDIT); // ... $data = json_decode($request->getContent()); $action = Filter::filterVar($data->action, FILTER_SANITIZE_SPECIAL_CHARS);

if ($action === 'fileRemove') { $file = Filter::filterVar($data->name, FILTER_SANITIZE_SPECIAL_CHARS); $file = PMF_CONTENT_DIR . '/user/images/' . $file;

if (file_exists($file)) { unlink($file); } // Returns success without checking if deletion was within intended directory } } ```

**Root Causes:** 1. **No path traversal prevention:** `FILTER_SANITIZE_SPECIAL_CHARS` does not…