ruby-saml has a SAML authentication bypass due to namespace handling (parser differential)

{
  "id": "da869c4f870b62582947731ab55cc998cbc48020d6a1840cecc6a19b972b2d2b",
  "url": "https://osv.dev/vulnerability/CVE-2025-66567",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ruby-saml has a SAML authentication bypass due to namespace handling (parser differential)",
    "summary": "The ruby-saml library is for implementing the client side of a SAML authorization. ruby-saml versions up to and including 1.12.4 contain an authentication bypass vulnerability due to an incomplete fix for CVE-2025-25292. ReXML and Nokogiri parse XML differently, generating entirely different document structures from the same input. This allows an attacker to execute a Signature Wrapping attack. This issue is fixed in version 1.18.0.",
    "evidence": "osv:CVE-2025-66567",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2025-66567",
      "aliases": [
        "CVE-2025-66567",
        "GHSA-9v8j-x534-2fx3"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/saml-toolkits/ruby-saml",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "6a7c040049babe748ee1bb4ca13898c47189114c"
                },
                {
                  "fixed": "e9c1cdbd0f9afa467b585de279db0cbd0fb8ae97"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:onelogin:ruby-saml:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.18.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "e9c1cdbd0f9afa467b585de279db0cbd0fb8ae97"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v1.17.0",
            "v1.12.2",
            "v1.16.0",
            "v1.15.0",
            "v1.14.0",
            "v1.12.1",
            "v1.12.0",
            "v1.11.0",
            "v1.10.2",
            "v1.10.1",
            "v1.10.0",
            "v1.9.0",
            "v1.8.0",
            "v1.7.2",
            "v1.7.1",
            "v1.7.0",
            "v1.6.2",
            "v1.6.1",
            "v0.9.2",
            "v1.6.0",
            "1.4.3",
            "1.5.0",
            "1.4.2",
            "1.4.1",
            "1.4.0",
            "1.3.1",
            "v1.3.0",
            "v1.2.0",
            "v1.1.2",
            "v1.1.1",
            "v1.1.0",
            "v1.0.0",
            "v0.9.1",
            "v0.9",
            "0.8.1",
            "0.8.0",
            "0.7.3",
            "v0.7.1",
            "v0.6.0",
            "v0.5.3",
            "v0.5.2",
            "v0.5.1",
            "v0.5.0",
            "v0.4.7",
            "v0.4.6",
            "v0.4.5",
            "v0.4.4",
            "v0.4.3",
            "v0.4.2",
            "v0.4.1",
            "v0.4.0",
            "v0.3.4",
            "v0.3.3",
            "v0.3.2",
            "v0.3.1",
            "v0.3.0",
            "v0.2.3",
            "v0.2.2",
            "v0.2.1",
            "v0.2.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-66567.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:34.654271196Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66567.json",
        "https://github.com/SAML-Toolkits/ruby-saml/security/advisories/GHSA-9v8j-x534-2fx3",
        "https://github.com/advisories/GHSA-754f-8gm6-c4r2",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-66567",
        "https://github.com/SAML-Toolkits/ruby-saml/commit/e9c1cdbd0f9afa467b585de279db0cbd0fb8ae97"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-347"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66567.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-66567",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 502062,
  "published_at": "2025-12-09T01:55:06.296+00:00"
}