Socket.IO: Engine.IO Protocol Revision Mismatch DoS

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

• CISA KEV Not listed.
• EPSS 0.0058, the 47th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

1. 31 Oct 2026, 13:34 UTC Confirmed by OSV

Sources

• GitHub Advisory Database: GHSA-2gc4-cqfq-p2gv
• OSV: GHSA-2gc4-cqfq-p2gv
• github.com/socketio/socket.io/security/advisories/GHSA-2gc4-cqfq-p2gv
• github.com/socketio/socket.io/commit/86db1fc3db2cd315a065d64c4e48918ccf9b4729
• github.com/socketio/socket.io
• github.com/socketio/socket.io/releases/tag/[email protected]

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.