What’s Vulnerable › Vulnerabilities

CVE-2023-31125: Uncaught exception in engine.io

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-05-08 · updated 2026-06-17
• Weakness: CWE-248

Description

Engine.IO is the implementation of transport-based cross-browser/cross-device bi-directional communication layer for Socket.IO. An uncaught exception vulnerability was introduced in version 5.1.0 and included in version 4.1.0 of the `socket.io` parent package. Older versions are not impacted. 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, including those who use depending packages like `socket.io`. This issue was fixed in version 6.4.2 of Engine.IO. There is no known workaround except upgrading to a safe version.

Affected products

• socketio engine.io: from 5.1.0 before 6.4.2 — fixed in 6.4.2

How to fix

Upgrade to a fixed version: socketio engine.io 6.4.2. Check the vendor advisory for mitigations.

References

• https://github.com/socketio/engine.io/commit/fc480b4f305e16fe5972cf337d055e598372dc44
• https://github.com/socketio/engine.io/releases/tag/6.4.2
• https://github.com/socketio/engine.io/security/advisories/GHSA-q9mw-68c2-j6m5
• https://security.netapp.com/advisory/ntap-20230622-0002/
• https://github.com/socketio/engine.io/commit/fc480b4f305e16fe5972cf337d055e598372dc44
• https://github.com/socketio/engine.io/releases/tag/6.4.2
• https://github.com/socketio/engine.io/security/advisories/GHSA-q9mw-68c2-j6m5
• https://security.netapp.com/advisory/ntap-20230622-0002/

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