Guzzle is an extensible PHP HTTP client. Prior to 7.12.3, CookieJar did not restrict cookies scoped to IP-address or bare-numeric Domain values to the exact host that set them, because SetCookie::matchesDomain() applied ordinary suffix matching to domains such as 192.168.0.1, [::1], or 1, allowing cross-host cookie disclosure, cookie injection, or session fixation. This issue is fixed in version 7.12.3.
https://github.com/guzzle/guzzle/security/advisories/GHSA-g446-98w2-8p5w
https://github.com/guzzle/guzzle/releases/tag/7.12.3
https://github.com/guzzle/guzzle/pull/3694
https://github.com/guzzle/guzzle/commit/b9944c161b12d9ee9c9334cfc5b9659ecd7451f8