CVE-2024-37890: Denial of service when handling a request with many HTTP headers in ws

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-06-17 · updated 2026-06-17
Weakness: CWE-476

Description

ws is an open source WebSocket client and server for Node.js. A request with a number of headers exceeding theserver.maxHeadersCount threshold could be used to crash a ws server. The vulnerability was fixed in ws@8.17.1 (e55e510) and backported to ws@7.5.10 (22c2876), ws@6.2.3 (eeb76d3), and ws@5.2.4 (4abd8f6). In vulnerable versions of ws, the issue can be mitigated in the following ways: 1. Reduce the maximum allowed length of the request headers using the --max-http-header-size=size and/or the maxHeaderSize options so that no more headers than the server.maxHeadersCount limit can be sent. 2. Set server.maxHeadersCount to 0 so that no limit is applied.

Affected products

websockets Ws: before 5.2.4; before 6.2.3; before 7.5.10; before 8.17.1; 2.1.0, 6.0.0, 7.0.0, 8.0.0 — fixed in 5.2.4, 6.2.3, 7.5.10, 8.17.1
Npm Ws: from 2.1.0 before 5.2.4; from 6.0.0 before 6.2.3; from 7.0.0 before 7.5.10; from 8.0.0 before 8.17.1 — fixed in 5.2.4, 6.2.3, 7.5.10, 8.17.1

How to fix

Upgrade to a fixed version: websockets Ws 5.2.4, 6.2.3, 7.5.10, 8.17.1; Npm Ws 5.2.4, 6.2.3, 7.5.10, 8.17.1. Check the vendor advisory for mitigations.

References

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