guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Prior to 2.12.3, Uri::assertValidHost() does not reject URI host components containing authority delimiters, embedded ports, or malformed IPv6 brackets, allowing Uri::getHost() to disagree with the URI authority used for security or routing decisions. This issue is fixed in version 2.12.3.
https://github.com/guzzle/psr7/security/advisories/GHSA-c2w2-prh8-qm98
https://github.com/guzzle/psr7/releases/tag/2.12.3
https://github.com/guzzle/psr7/pull/811
https://github.com/guzzle/psr7/commit/ddd64f17d4cc1f7e5ffe6fd2c989ec7221712580