guzzlehttp/guzzle versions before 7.15.1 fail to preserve host-only cookie scope, storing the request host in the Domain field instead of marking cookies as host-only. Attackers controlling child hosts can receive host-only cookies intended only for parent hosts, potentially disclosing session identifiers and authorization tokens when the same cookie jar is reused across trust boundaries.
https://www.vulncheck.com/advisories/guzzlehttp-guzzle-before-host-only-cookie-scope
https://github.com/guzzle/guzzle/security/advisories/GHSA-wm3w-8rrp-j577
Published: 2026-08-01
Updated: 2026-08-01
Base Score: 5.4
Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:N/A:N
Severity: Medium
Base Score: 5.9
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Severity: Medium
Base Score: 8.2
Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Severity: High