Socket.IO enables bidirectional and low-latency communication for every platform. From 6.5.0 before 6.6.7, Engine.IO servers with WebTransport enabled can resolve a crafted session ID such as __proto__ through an inherited property of the clients object during WebTransport upgrade handling, causing a TypeError and denial of service. This issue is fixed in version 6.6.7.
Fix
Patch, vendor advisory and mitigation references on NVD 2
- https://github.com/socketio/socket.io/commit/1fa1f46cd420ac5b57bb4c04c959b58f3c79158c Patch
- https://github.com/socketio/socket.io/security/advisories/GHSA-gr94-w7qr-f4j3 Patch, Vendor Advisory, Mitigation
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 7.5 · socketNVD modified 2026-10-25 20:10
Affected (CPE criteria) 1
cpe:2.3:a:socket:engine.io:*:*:*:*:*:node.js:*:*