CVE-2026-54458: AVideo: Unauthenticated Stored DOM Cross-Site Scripting via Per-Client Metadata Broadcast in YPTSocket Plugin

WWBN AVideo is an open source video platform. Versions prior to 29.0 contain a stored DOM Cross-Site Scripting vulnerability in the YPTSocket plugin. Any unauthenticated remote attacker can execute arbitrary JavaScript in the authenticated origin of every administrator currently viewing a page that renders the YPTSocket online-users debug panel. plugin/YPTSocket/getWebSocket.json.php issues a signed WebSocket token to any anonymous caller, and MessageSQLiteV2::onOpen at plugin/YPTSocket/MessageSQLiteV2.php lines 91 and 110 reads the attacker-controlled webSocketSelfURI and pagetitle query parameters from the WebSocket connection URL with no validation. Both values persist into the in-memory SQLite connections table and broadcast inside the usersidonline array sent to every connected client; on the client, plugin/YPTSocket/script.js::updateSocketUserCard interpolates the broadcast pagetitle into an HTML template literal that is passed to jQuery $.append(html), which parses attacker bytes into live DOM nodes including <img> with inline event handlers. Successful attackers can can read non-HttpOnly cookies and the CSRF token rendered into the admin dashboard, issue authenticated requests to any admin-only endpoint, exfiltrate the admin dashboard DOM, and chain into any admin-context mutation. When the victim is an AVideo administrator, the attacker turns a single anonymous WebSocket connection into full administrative takeover via the admin's own session. This issue has been patched by https://github.com/WWBN/AVideo/commit/8be71e53ccbe9b84b30870db386fb4d2b11e1c16.