Impact
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 3rd-party site or a malicious attacker who can control the redirection target (ie. an open redirector) to leak the cookie to the 3rd party site.
Patches
This was patched in e041de359221ebeae04c469e8aff4145764e6d76.
Workarounds
There are no known workarounds.
References
ranjit-git Reporter
KhafraDev Remediation developer
mcollina Coordinator
Impact
Undici already cleared Authorization headers on cross-origin redirects, but did not clear
Cookieheaders. By design,cookieheaders 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 3rd-party site or a malicious attacker who can control the redirection target (ie. an open redirector) to leak the cookie to the 3rd party site.
Patches
This was patched in e041de359221ebeae04c469e8aff4145764e6d76.
Workarounds
There are no known workarounds.
References