CVE-2026-18089

{
  "id": "CVE-2026-18089",
  "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
  "published": "2026-08-03T14:16:24.890",
  "lastModified": "2026-10-23T21:10:00.157",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Net::SAML2 versions before 0.86 for Perl allow SAML authentication bypass by verifying responses against the response-embedded certificate in verify_xml when no trust anchor is configured.\n\nverify_xml in Net::SAML2::Role::VerifyXML runs \"return if !$anchors && !$cacert;\" as soon as the XML::Sig check succeeds, and that check uses the X.509 certificate taken from the response's own dsig:KeyInfo/dsig:X509Certificate element, so an unanchored response is checked only against the key it carries. Binding::POST declares cacert as an optional Maybe[Str] with no default, so a POST binding built without one takes that path, and _verify_encrypted_assertion returns early the same way with \"return $xml unless $cacert;\".\n\nAny caller that constructs Binding::POST or calls Assertion->new_from_xml without a cacert, cert_text, or anchors argument accepts a response signed by an attacker generated key whose self-signed certificate is embedded in that response, authenticating an arbitrary assertion."
    },
    {
      "lang": "es",
      "value": "Las versiones de Net::SAML2 anteriores a la 0.86 para Perl permiten la omisión de autenticación SAML al verificar las respuestas contra el certificado incrustado en la respuesta en verify_xml cuando no se configura un ancla de confianza.\n\nverify_xml en Net::SAML2::Role::VerifyXML ejecuta ’return if !$anchors && !$cacert;’ tan pronto como la verificación de XML::Sig tiene éxito, y esa verificación utiliza el certificado X.509 tomado del propio elemento dsig:KeyInfo/dsig:X509Certificate de la respuesta, por lo que una respuesta sin ancla se verifica solo contra la clave que lleva. Binding::POST declara cacert como un Maybe[Str] opcional sin valor predeterminado, por lo que un enlace POST construido sin uno toma ese camino, y _verify_encrypted_assertion retorna temprano de la misma manera con ’return $xml unless $cacert;’.\n\nCualquier llamador que construya Binding::POST o llame a Assertion  ->  new_from_xml sin un argumento cacert, cert_text o anchors acepta una respuesta firmada por una clave generada por un atacante cuyo certificado autofirmado está incrustado en esa respuesta, autenticando una aserción arbitraria."
    }
  ],
  "affected": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "affectedData": [
        {
          "vendor": "TIMLEGGE",
          "product": "Net::SAML2",
          "defaultStatus": "unaffected",
          "collectionURL": "https://cpan.org/modules",
          "packageName": "Net-SAML2",
          "programFiles": [
            "lib/Net/SAML2/Role/VerifyXML.pm",
            "lib/Net/SAML2/Binding/POST.pm",
            "lib/Net/SAML2/Protocol/Assertion.pm"
          ],
          "programRoutines": [
            {
              "name": "Net::SAML2::Role::VerifyXML::verify_xml"
            },
            {
              "name": "Net::SAML2::Binding::POST::handle_response"
            },
            {
              "name": "Net::SAML2::Protocol::Assertion::_verify_encrypted_assertion"
            }
          ],
          "repo": "https://github.com/perl-net-saml2/perl-Net-SAML2",
          "versions": [
            {
              "version": "0",
              "lessThan": "0.86",
              "versionType": "custom",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
          "baseScore": 7.5,
          "baseSeverity": "HIGH",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "availabilityImpact": "NONE"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 3.6
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-08-03T19:56:09.872860Z",
          "id": "CVE-2026-18089",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-295"
        },
        {
          "lang": "en",
          "value": "CWE-347"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:timlegge:net\\:\\:saml2:*:*:*:*:*:perl:*:*",
              "versionEndExcluding": "0.86",
              "matchCriteriaId": "69FF1709-62F7-4E8C-B90D-ABFA96B07FF1"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Binding/POST.pm#L21",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "tags": [
        "Product"
      ]
    },
    {
      "url": "https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Protocol/Assertion.pm#L84",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "tags": [
        "Product"
      ]
    },
    {
      "url": "https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Role/VerifyXML.pm#L32",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "tags": [
        "Product"
      ]
    },
    {
      "url": "https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.88/source/Changes",
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "tags": [
        "Release Notes"
      ]
    }
  ]
}