Uncaught Exception in engine.io

Description

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.

Scores

EPSS (exploitation in 30 days)

2.9% · top 13% of all CVEs (6 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: yes · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Weakness

• CWE-754: Improper Check for Unusual or Exceptional Conditions (opens in a new tab)All about CWE-754 and its CVEs
• CWE-755 (opens in a new tab)All about CWE-755 and its CVEs

Affected products

• socketio · engine.io

  • affected >= 4.0.0, < 4.1.2
  • affected >= 5.0.0, < 5.2.1
  • affected >= 6.0.0, < 6.1.1

Affected packages

From reviewed advisories of the GitHub Advisory Database.

• npmengine.ioGHSA-273r-mgr4-v34f (opens in a new tab)

References (8)

• https://github.com/socketio/engine.io/security/advisories/GHSA-273r-mgr4-v34f (opens in a new tab)x_refsource_CONFIRMx_transferred
• https://github.com/socketio/engine.io/commit/66f889fc1d966bf5bfa0de1939069153643874ab (opens in a new tab)x_refsource_MISCx_transferred
• https://github.com/socketio/engine.io/commit/a70800d7e96da32f6e6622804ef659ebc58659db (opens in a new tab)x_refsource_MISCx_transferred
• https://github.com/socketio/engine.io/commit/c0e194d44933bd83bf9a4b126fca68ba7bf5098c (opens in a new tab)x_refsource_MISCx_transferred
• https://github.com/socketio/engine.io/releases/tag/4.1.2 (opens in a new tab)x_refsource_MISCx_transferred
• https://github.com/socketio/engine.io/releases/tag/5.2.1 (opens in a new tab)x_refsource_MISCx_transferred
• https://github.com/socketio/engine.io/releases/tag/6.1.1 (opens in a new tab)x_refsource_MISCx_transferred
• https://security.netapp.com/advisory/ntap-20220209-0002/ (opens in a new tab)x_refsource_CONFIRMx_transferred

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisory GHSA-273r-mgr4-v34f (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2022-21676](https://trackcve.app/badge/CVE-2022-21676.svg)](https://trackcve.app/cve/CVE-2022-21676)

Record last updated 23 Apr 2025, 19:13 UTC.