CVE-2022-21676: Socket Engine.io

High severity, CVSS 7.5. EPSS: 2.8% chance of exploitation in the next 30 days.

Engine.IO is the implementation of transport-based cross-browser/cross-device bi-directional communication layer for Socket.IO. A specially crafted HTTP request can trigger an uncaught exception on the Engine.IO server, thus killing the Node.js process. This impacts all the users of the `engine.io` package starting from version `4.0.0`, including those who uses depending packages like `socket.io`. Versions prior to `4.0.0` are not impacted. A fix has been released for each major branch, namely `4.1.2` for the `4.x.x` branch, `5.2.1` for the `5.x.x` branch, and `6.1.1` for the `6.x.x` branch. There is no known workaround except upgrading to a safe version.

Affected products

• Socket Engine.io: from 4.0.0, before 4.1.2 (fixed in 4.1.2); from 5.0.0, before 5.2.1 (fixed in 5.2.1); from 6.0.0, before 6.1.1 (fixed in 6.1.1)

Published 2022-01-12. Last modified 2026-06-17.