Your submission was sent successfully! Close

You have successfully unsubscribed! Close

Thank you for signing up for our newsletter!
In these regular emails you will find the latest updates about Ubuntu and upcoming events where you can meet our team.Close


Published: 12 October 2023

Undici is an HTTP/1.1 client written from scratch for Node.js. Prior to version 5.26.2, Undici already cleared Authorization headers on cross-origin redirects, but did not clear `Cookie` headers. By design, `cookie` headers are forbidden request headers, disallowing them to be set in RequestInit.headers in browser environments. Since undici handles headers more liberally than the spec, there was a disconnect from the assumptions the spec made, and undici's implementation of fetch. As such this may lead to accidental leakage of cookie to a third-party site or a malicious attacker who can control the redirection target (ie. an open redirector) to leak the cookie to the third party site. This was patched in version 5.26.2. There are no known workarounds.



Cvss 3 Severity Score


Score breakdown


Package Release Status
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Does not exist

jammy Does not exist

lunar Ignored
(end of life, was needs-triage)
mantic Needs triage

trusty Does not exist

Released (5.26.3+dfsg1+~cs23.10.12-1)
xenial Does not exist


Severity score breakdown

Parameter Value
Base score 3.5
Attack vector Network
Attack complexity Low
Privileges required Low
User interaction Required
Scope Unchanged
Confidentiality Low
Integrity impact None
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:N