CVE-2026-9679

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.
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*

History

25 Jun 2026, 17:43

Type Values Removed Values Added
References () https://cna.openjsf.org/security-advisories.html - () https://cna.openjsf.org/security-advisories.html - Vendor Advisory
References () https://github.com/nodejs/undici/security/advisories/GHSA-p88m-4jfj-68fv - () https://github.com/nodejs/undici/security/advisories/GHSA-p88m-4jfj-68fv - Vendor Advisory, Mitigation
CPE cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
First Time Nodejs
Nodejs undici

17 Jun 2026, 20:20

Type Values Removed Values Added
New CVE

Information

Published : 2026-06-17 18:18

Updated : 2026-06-25 17:43


NVD link : CVE-2026-9679

Mitre link : CVE-2026-9679

CVE.ORG link : CVE-2026-9679


JSON object : View

Products Affected

nodejs

  • undici
CWE
CWE-93

Improper Neutralization of CRLF Sequences ('CRLF Injection')