Vulnerability Description
Guzzle is an extensible PHP HTTP client. Prior to 7.12.1, CookieJar incorrectly accepts cookies with a dot-only Domain attribute and whitespace-padded variants. SetCookie::matchesDomain() removes leading dots from the cookie domain, normalizing dot-only values to the empty string; SetCookie::validate() only rejected a strictly empty domain, so these cookies could be stored and the empty normalized domain was treated as matching any request host. An attacker-controlled origin that an application requests with a shared cookie jar can therefore set a cookie that Guzzle later sends to unrelated hosts using the same jar. This may allow cookie injection or session fixation against downstream services, depending on how those services interpret the injected cookie. This vulnerability is fixed in 7.12.1.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Guzzlephp | Guzzle | < 7.12.1 |
Related Weaknesses (CWE)
References
- https://github.com/FriendsOfPHP/security-advisories/blob/master/guzzlehttp/guzzl
- https://github.com/guzzle/guzzle/commit/7f537cded1912349abf5081258d6db19106d774d
- https://github.com/guzzle/guzzle/pull/3653
- https://github.com/guzzle/guzzle/releases/tag/7.12.1
- https://github.com/guzzle/guzzle/security/advisories/GHSA-cwxw-98qj-8qjxThird Party Advisory
FAQ
What is CVE-2026-55767?
CVE-2026-55767 is a vulnerability with a CVSS score of 5.8 (MEDIUM). Guzzle is an extensible PHP HTTP client. Prior to 7.12.1, CookieJar incorrectly accepts cookies with a dot-only Domain attribute and whitespace-padded variants. SetCookie::matchesDomain() removes lead...
How severe is CVE-2026-55767?
CVE-2026-55767 has been rated MEDIUM with a CVSS base score of 5.8/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-55767?
Check the references section above for vendor advisories and patch information. Affected products include: Guzzlephp Guzzle.