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osvGoogleOSV:GHSA-WQQ4-5WPV-MX2G
HistoryOct 16, 2023 - 2:05 p.m.

Undici's cookie header not cleared on cross-origin redirect in fetch

2023-10-1614:05:37
Google
osv.dev
12
undici
cookie header
cross-origin redirect
fetch
forbidden request headers
accidental leakage
patches
version 5.26.2

6.5 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

LOW

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

0.009 Low

EPSS

Percentile

82.4%

Impact

Undici clears Authorization headers on cross-origin redirects, but does 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 specification, 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, which is included in version 5.26.2.

CPENameOperatorVersion
undicilt5.26.2

References

6.5 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

LOW

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

0.009 Low

EPSS

Percentile

82.4%