{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "simplesamlphp/saml2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.0.0"
            },
            {
              "fixed": "6.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "simplesamlphp/saml2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.0.0"
            },
            {
              "fixed": "5.0.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "simplesamlphp/saml2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.20.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "simplesamlphp/saml2-legacy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.20.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-49283"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-02T20:25:56Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Summary\n\nSimpleSAMLphp\u0027s HTTP-Artifact receive path can treat an unsigned embedded SAML `Response` as cryptographically valid for the wrong IdP.\n\nIn the `HTTPArtifact::receive()` flow, the SOAP `ArtifactResponse` receives a TLS-based validator from `SOAPClient::addSSLValidator()`. The embedded SAML `Response` then receives a validator that delegates signature validation to that outer `ArtifactResponse`. Later, the SP validates the embedded `Response` against metadata selected from the embedded response issuer, not necessarily the artifact issuer.\n\nThe critical issue is that `SOAPClient::validateSSL()` returns normally when the TLS public key does not match the key currently being validated. `SAML2\\Message::validate()` treats any validator call that does not throw an exception as successful. As a result, an `ArtifactResponse` obtained from one IdP can validate an unsigned embedded SAML `Response` that claims to be issued by a different IdP.\n\nIn a multi-IdP/federation deployment where a malicious or lower-trust IdP can issue an HTTP-Artifact response to an SP, this can allow the attacker to authenticate to the SP as arbitrary users from a higher-trust victim IdP.\n\n## Impact\n\nA malicious or lower-trust IdP in the same SP/federation trust set can authenticate to the SP as users from another IdP when HTTP-Artifact is used. The attacker can choose assertion attributes, `NameID`, and session data in the forged unsigned assertion.\n\nThis is an authentication bypass and identity-provider impersonation issue. In realistic federations, the security boundary between IdPs matters: a compromised or low-assurance IdP should not be able to mint identities for a high-assurance IdP.",
  "id": "GHSA-6929-8p9f-26jx",
  "modified": "2026-07-02T20:25:56Z",
  "published": "2026-07-02T20:25:56Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/simplesamlphp/saml2/security/advisories/GHSA-6929-8p9f-26jx"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/simplesamlphp/saml2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "SimpleSAMLphp HTTP-Artifact TLS validator confusion allows cross-IdP authentication bypass"
}