---
title: "CVE-2026-40911: WWBN AVideo YPTSocket WebSocket Broadcast Relay Leads to Unauthenticated Cross-User JavaScript Execution via Client-Side eval() Sinks"
url: https://erroneo.us/security/cve/CVE-2026-40911/
description: "CVE-2026-40911 (wwbn/avideo (Composer (PHP))): WWBN AVideo is an open source video platform. In versions 29.0 and prior, the YPTSocket plugin's WebSocket…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-04-21
date_modified: 2026-04-24
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-40911"
kev: false
cvss: 10
epss: 0.00859
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-40911: WWBN AVideo YPTSocket WebSocket Broadcast Relay Leads to Unauthenticated Cross-User JavaScript Execution via Client-Side eval() Sinks

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.9% , percentile 58: FIRST’s model estimates a 0.9% chance of exploitation activity in the next 30 days, higher than 58% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes wwbn/avideo (Composer (PHP)) <= 29.0, no fixed version listed . Check your lockfile, including transitive dependencies.

## What it is

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.

## Affected packages

- Composer (PHP) `wwbn/avideo` <= 29.0 → fixed: none listed

## Affected products (CVE record)

- WWBN AVideo: <= 29.0

## Severity

- GitHub_M CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 10.0 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.86% probability of exploitation activity in the next 30 days; percentile 58.

## Sources

- [GitHub Advisory GHSA-gph2-j4c9-vhhr](https://github.com/advisories/GHSA-gph2-j4c9-vhhr)
- [CVE.org record CVE-2026-40911](https://www.cve.org/CVERecord?id=CVE-2026-40911)
- [NVD entry CVE-2026-40911](https://nvd.nist.gov/vuln/detail/CVE-2026-40911)
- [github.com](https://github.com/WWBN/AVideo/security/advisories/GHSA-gph2-j4c9-vhhr)
- [github.com](https://github.com/WWBN/AVideo/commit/c08694bf6264eb4decceb78c711baee2609b4efd)

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Source page: https://erroneo.us/security/cve/CVE-2026-40911/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt