5.9

CVE-2026-9679

undici vulnerable to HTTP header injection via Set-Cookie percent-decoding

Impact:
undici's cookie parser in parseSetCookie percent-decodes cookie values via qsUnescape, turning encoded sequences like %0D%0A, %00, %3B, and %3D into their literal byte equivalents. RFC 6265 §5.4 does not specify any decoding and browsers do not decode either.

Applications that parse a Set-Cookie header and then forward the parsed value into a response header (proxies, middleware, SSR frameworks) become vulnerable to HTTP response header injection: an attacker-controlled upstream can inject arbitrary Set-Cookie, Location, or Cache-Control headers into the application's downstream response, enabling session fixation, open redirect, or cache poisoning.

Affected applications are those that use undici's cookie parsing (parseSetCookie, parseCookie, getSetCookies) and forward the parsed cookie value into a response header.

This was introduced in undici 7.0.0 via PR #3789.

Patches:
Upgrade to undici v6.26.0, v7.28.0 or v8.5.0.

Workarounds:
If upgrade is not immediately possible, do not forward values returned by parseSetCookie/parseCookie/getSetCookies directly into response headers; sanitize the value first to strip or reject CR, LF, NUL, ;, and = bytes.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Nodejs ≫ Undici SwPlatformnode.js Version < 6.27.0
Nodejs ≫ Undici SwPlatformnode.js Version >= 7.0.0 < 7.28.0
Nodejs ≫ Undici SwPlatformnode.js Version >= 8.0.0 < 8.5.0
Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.26% 0.168
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
ce714d77-add3-4f53-aff5-83d477b104bb 5.9 2.2 3.6
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
CWE-93 Improper Neutralization of CRLF Sequences ('CRLF Injection')

The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.

https://cna.openjsf.org/security-advisories.html
Vendor Advisory
https://github.com/nodejs/undici/security/advisories/GHSA-p88m-4jfj-68fv
Vendor Advisory
Mitigation