What is CVE-2026-2229?

CVE-2026-2229 is a high-severity vulnerability in Undici, classified under CWE-248. CVSS score: 7.5/10. Published 2026-03-12.

How severe is CVE-2026-2229?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Undici

CVE-2026-2229

ImpactThe undici WebSocket client is vulnerable to a denial-of-service attack due to improper validation of the server_max_window_bits parameter in the permessage-deflate extension. When a WebSocket client connects to a server, it automati…

EPSS: 0.002 (38.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Undici — versions < 6.24.0; 7.0.0 < 7.24.0, 6.24.0: 7.24.0

Weakness classification (CWE)

CWE-248
CWE-1284 — Improper Validation of Specified Quantity in Input

References

github.com/nodejs/undici/security/advisories/GHSA-v9p9-hfj2-hcw8
hackerone.com/reports/3487486
cna.openjsf.org/security-advisories.html
datatracker.ietf.org/doc/html/rfc7692
nodejs.org/api/zlib.html

Frequently asked questions

What is CVE-2026-2229?: CVE-2026-2229 is a high-severity vulnerability in Undici, classified under CWE-248. CVSS score: 7.5/10. Published 2026-03-12.
How severe is CVE-2026-2229?: High severity. CVSS v3 base score is 7.5 out of 10.