GHSA-xggw-g9pm-9qhh AVideo has PHP Code Injection via eval() in Gallery saveSort.json.php Exploitable Through CSRF Against Admin

• Packagist wwbn/avideo: <= 26.0 (no fix yet)

Summary The Gallery plugin's `saveSort.json.php` endpoint passes unsanitized user input from `$_REQUEST['sections']` array values directly into PHP's `eval()` function. While the endpoint is gated behind `User::isAdmin()`, it has no CSRF token validation. Combined with AVideo's explicit `SameSite=None` session cookie configuration, an attacker can exploit this via cross-site request forgery to achieve unauthenticated remote code execution — requiring only that an admin visits an attacker-controlled page. Details Vulnerable code — `plugin/Gallery/view/saveSort.json.php:20-25`: ```php if(!empty($_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 `$_REQUEST['sections']` is interpolated directly into the string passed to `eval()` with no sanitization — no allowlist, no regex validation, no escaping. Normal Gallery usage sends section names like `'Shorts'`, `'Trending'`, etc. from jQuery UI sortable, but the server enforces no such constraint. CSRF enablement — `objects/include_config.php:134-137`: ```php if ($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: ```html document.getElementById('exploit').submit(); ``` 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: ```php $object->x=1;system(base64_decode('aWQ7aG9zdG5hbWU='));//Order = 0; ``` This breaks out of the property assignment, calls `system()` with attacker-controlled arguments, and comments out the rest of the line. The response JSON will contain the command output, but even without seeing the response, the command executes server-side. Expected result: The `id` and `hostname` commands execute on the server under the web server's user context. Impact • Remote Code Execution — An attacker achieves arbitrary PHP code execution on the server by luring an admin to visit a malicious page. No prior authentication or account on the target is required. • Full server compromise — The attacker can read/write files, access the database, pivot to other services, install backdoors, or exfiltrate data. • Stealth — The attack is a single form submission that completes in milliseconds. The admin may not notice anything unusual. • Blast radius — Any AVideo instance running over HTTPS (which triggers `SameSite=None`) where an admin can be lured to click a link is vulnerable. Recommended Fix Primary fix — Replace `eval()` with an allowlist check: In `plugin/Gallery/view/saveSort.json.php`, replace lines 20-26: ```php if(!empty($_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`: ```php 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.