CVE-2021-32640

Name: CVE-2021-32640
Creator: NVD / NIST
Published: 2021-05-25T19:15:07.767+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 2.94%

Last modified Jun 17, 2026

CVE-2021-32640 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. ws is an open source WebSocket client and server library for Node.js. A specially crafted value of the `Sec-Websocket-Protocol` header can be used to significantly slow down a ws server. EPSS estimates a 2.94% chance of exploitation in the next 30 days.

Description

ws is an open source WebSocket client and server library for Node.js. A specially crafted value of the `Sec-Websocket-Protocol` header can be used to significantly slow down a ws server. The vulnerability has been fixed in ws@7.4.6 (https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ff). In vulnerable versions of ws, the issue can be mitigated by reducing the maximum allowed length of the request headers using the [`--max-http-header-size=size`](https://nodejs.org/api/cli.html#cli_max_http_header_size_size) and/or the [`maxHeaderSize`](https://nodejs.org/api/http.html#http_http_createserver_options_requestlistener) options.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS Probability

2.94%

85.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Ws Project	Ws	>= 5.0.0, < 6.2.2
Ws Project	Ws	>= 7.0.0, < 7.4.6
Netapp	E-Series Performance Analyzer	All versions

References

https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ffPatch, Third Party Advisory
https://github.com/websockets/ws/security/advisories/GHSA-6fc8-4gx4-v693Exploit, Mitigation, Patch, Third Party Advisory
https://lists.apache.org/thread.html/rdfa7b6253c4d6271e31566ecd5f30b7ce1b8fb2c89d52b8c4e0f4e30%40%3Ccommits.tinkerpop.apache.org%3E
https://security.netapp.com/advisory/ntap-20210706-0005/Third Party Advisory
https://github.com/websockets/ws/commit/00c425ec77993773d823f018f64a5c44e17023ffPatch, Third Party Advisory
https://github.com/websockets/ws/security/advisories/GHSA-6fc8-4gx4-v693Exploit, Mitigation, Patch, Third Party Advisory
https://lists.apache.org/thread.html/rdfa7b6253c4d6271e31566ecd5f30b7ce1b8fb2c89d52b8c4e0f4e30%40%3Ccommits.tinkerpop.apache.org%3E
https://security.netapp.com/advisory/ntap-20210706-0005/Third Party Advisory

Timeline

Published: May 25, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-32640?

How severe is CVE-2021-32640?

CVE-2021-32640 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 2.94% probability of exploitation in the next 30 days.

How do I fix CVE-2021-32640?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-32640?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST