CVE-2026-40911 WWBN AVideo YPTSocket WebSocket Broadcast Relay Leads to Unauthenticated Cross-User JavaScript Execution via Client-Side eval() Sinks
Unauthenticated attackers can execute arbitrary JavaScript in all connected users' browsers via unsanitized WebSocket messages, leading to account takeover.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-40911?
CVE-2026-40911 is a critical cross-site scripting vulnerability in Wwbn Avideo, published on 21 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
WWBN AVideo is an open source video platform. In versions 29.0 and prior, the YPTSocket plugin's WebSocket server relays attacker-supplied JSON message bodies to every connected client without sanitizing the `msg` or `callback` fields. On the client side, `plugin/YPTSocket/script.js` contains two `eval()` sinks fed directly by those relayed fields (`json.msg.autoEvalCodeOnHTML` at line 568 and `json.callback` at line 95). Because tokens are minted for anonymous visitors and never revalidated beyond decryption, an unauthenticated attacker can broadcast arbitrary JavaScript that executes in the origin of every currently-connected user (including administrators), resulting in universal account takeover, session theft, and privileged action execution. Commit c08694bf6264eb4decceb78c711baee2609b4efd contains a fix.
Weakness: CWE-94
Which versions are affected by CVE-2026-40911?
2 open source packages ship an affected version, including wwbn/avideo. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
wwbn/avideo Packagist | All versions to 29.0 | None |
wwbn/avideo Packagist | All versions to 29.0 | None |
Products include Wwbn Avideo.
How do I fix CVE-2026-40911?
No fix has been published for CVE-2026-40911 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-40911 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40911 exists.
Other vulnerabilities in Wwbn Avideo
- CVE-2026-33478 AVideo Multi-Chain Attack: Unauthenticated Remote Code Execution via Clone Key Disclosure, Database Dump, and Command Injection
- CVE-2022-30534 Command injection in AVideo
- CVE-2022-30547 Path traversal in AVideo
- CVE-2022-32572 Command injection in AVideo
- CVE-2026-33352 AVideo has an Unauthenticated SQL Injection via `doNotShowCats` Parameter (Backslash Escape Bypass)
Sources
Also known as GHSA-gph2-j4c9-vhhr.