Vulnerability · Published Aug 1, 2026 · Assigned by VulnCheck

CVE-2026-67355guzzlehttp/guzzle before 7.15.1 Host-only Cookie Scope

Medium 5.9

In plain English

A medium-severity security flaw in guzzle from guzzle. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)5.9Medium

Exploit odds (30 days)0.4%top 69.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:12	guzzle	no fix listed	DEBIAN-CVE-2026-67355
Debian:13	guzzle	no fix listed	DEBIAN-CVE-2026-67355
Debian:14	guzzle	7.15.1-1	DEBIAN-CVE-2026-67355
Packagist	guzzlehttp/guzzle	7.15.1	GHSA-wm3w-8rrp-j577
Ubuntu:24.04:LTS	guzzle	no fix listed	UBUNTU-CVE-2026-67355
Ubuntu:26.04:LTS	guzzle	no fix listed	UBUNTU-CVE-2026-67355
Ubuntu:26.10	guzzle	no fix listed	UBUNTU-CVE-2026-67355

Affected products (as reported)

Vendor	Product	Versions
guzzle	guzzle	0 – before 7.15.1

Weakness: CWE-201 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

References

GitHub Security Advisory (GHSA-wm3w-8rrp-j577) vendor-advisory
VulnCheck Advisory: guzzlehttp/guzzle before 7.15.1 Host-only Cookie Scope third-party-advisory