WWBN AVideo: Stored XSS via autoEvalCodeOnHTML Bypass in MessageSQLite WebSocket Handler (CVE-2026-43874 Bypass)

WWBN AVideo is an open source video platform. Versions 29.0 and below contain a Stored XSS vulnerability through the autoEvalCodeOnHTML parameter in the MessageSQLite WebSocket Handler. 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. An authenticated attacker can execute arbitrary JavaScript in any connected user's browser session via the WebSocket messaging system, stealing session cookies and authentication tokens, taking over accounts through session hijacking, and chaining with CSRF to perform admin actions on the victim's behalf, in the default SQLite WebSocket backend configuration. This issue has a patch that has yet to be officially released, see https://github.com/WWBN/AVideo/commit/3e0b3ce2bfa766183ff0ae227439394db57b1a23.