{"id":"CVE-2026-48998","aliases":["GHSA-34xg-wgjx-8xph"],"url":"https://o3.security/vulnerability/CVE-2026-48998","summary":"guzzlehttp/psr7 has Host Confusion via Authority Reinterpretation","details":"guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Versions prior to 2.10.2 contain improper Host header validation when parsing raw HTTP request messages and when deriving a server request URI from server variables. An attacker can provide a malformed Host header containing URI authority delimiters, such as `trusted.example@evil.example`. When the Host value is used to construct a URI, the malformed value can be reinterpreted as URI userinfo and host. This can cause the PSR-7 request URI host to differ from the original Host header value. Applications are affected if they parse attacker-controlled raw HTTP requests with `GuzzleHttp\\Psr7\\Message::parseRequest()` or the legacy 1.x `GuzzleHttp\\Psr7\\parse_request()` function, or if they build server requests from attacker-controlled server variables, then rely on the resulting URI host for routing, allow-list checks, or forwarding decisions. In affected forwarding or gateway scenarios, this may cause requests or credentials to be sent to an unintended host. The issue is patched in `2.10.2`. `1.x` is end-of-life and will not receive a patch. Some workarounds are available. Validate the `Host` header as `uri-host [ \":\" port ]` before calling `Message::parseRequest()` or legacy `parse_request()` on untrusted HTTP request data, or before deriving routing and forwarding decisions from a parsed request URI. Reject Host values containing userinfo, path, query, or fragment delimiters.","published":"2026-06-11T12:34:32.397Z","modified":"2026-08-12T03:51:19.073036526Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"},"epss":{"score":0.00198,"percentile":0.09555,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Packagist","name":"guzzlehttp/psr7","fixedVersion":"2.10.2"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48998.json"},{"type":"ADVISORY","url":"https://github.com/guzzle/psr7/security/advisories/GHSA-34xg-wgjx-8xph"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-48998"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:19.073036526Z"}}