guzzlehttp/psr7 has Host Confusion via Authority Reinterpretation

{
  "id": "20cfc2d55359bca1a9bdb9306e0685b62462cb2ba5778bf937f02635be2e5e05",
  "url": "https://osv.dev/vulnerability/CVE-2026-48998",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "guzzlehttp/psr7 has Host Confusion via Authority Reinterpretation",
    "summary": "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.",
    "evidence": "osv:CVE-2026-48998",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-48998",
      "aliases": [
        "CVE-2026-48998",
        "GHSA-34xg-wgjx-8xph"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/guzzle/psr7",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "a1bbdc172f32a25fe999965b65b6e71fd87da9ed"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.10.2"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StringRangeExpression"
                  },
                  {
                    "cpe": "cpe:2.3:a:guzzlephp:psr-7:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.10.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "2.10.1",
            "2.10.0",
            "2.9.0",
            "2.8.1",
            "2.8.0",
            "2.7.1",
            "2.7.0",
            "2.6.3",
            "2.6.2",
            "2.6.1",
            "2.6.0",
            "2.5.0",
            "2.4.4",
            "2.4.3",
            "2.4.2",
            "2.4.1",
            "2.4.0",
            "2.3.0",
            "2.2.2",
            "2.2.1",
            "2.2.0",
            "2.1.0",
            "2.0.0",
            "2.0.0-rc1",
            "2.0.0-beta1",
            "1.6.0",
            "1.5.0",
            "1.5.2",
            "1.5.1",
            "1.4.2",
            "1.4.1",
            "1.4.0",
            "1.3.1",
            "1.3.0",
            "1.2.3",
            "1.2.2",
            "1.2.1",
            "1.2.0",
            "1.1.0",
            "1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-48998.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:27.703844615Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48998.json",
        "https://github.com/guzzle/psr7/security/advisories/GHSA-34xg-wgjx-8xph",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-48998"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-20",
          "CWE-918"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/48xxx/CVE-2026-48998.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-48998",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 494317,
  "published_at": "2026-06-11T12:34:32.397+00:00"
}