FKIE_CVE-2026-18092

Vulnerability from fkie_nvd - Published: 2026-08-03 14:16 - Updated: 2026-10-23 21:10
Severity
8.1 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
Summary
Net::SAML2 versions before 0.86 for Perl allow SAML authentication bypass via XML signature wrapping because new_from_xml reads assertion identity with document-wide XPath instead of the signed subtree. new_from_xml reads the NameID, attribute values, SessionIndex, audience and other identity fields with document-wide XPath, such as //saml:Assertion/saml:AttributeStatement/saml:Attribute and //saml:Subject/saml:NameID, which select the first matching element in document order rather than the element covered by the verified signature. handle_response confirms that a signature is present and, when a cacert is configured, that it chains to the CA, but XML::Sig verifies only the element named by the signature's Reference URI, so unsigned sibling assertions in the same document are not covered. An attacker who holds any one IdP-signed assertion can add an unsigned attacker-authored assertion earlier in document order; the signature still verifies and the document-order XPath returns the attacker's NameID and attributes. Any caller that passes an untrusted Response to new_from_xml can accept identity fields from an assertion the IdP never signed, even when a cacert trust anchor is configured, so a party holding one valid IdP-signed assertion can authenticate as an arbitrary user.
References
9b29abf9-4ab0-4765-b253-1875cd9b441ehttps://github.com/perl-net-saml2/perl-Net-SAML2/commit/201fead7f42b83f40c84bf4a311a25b09acd18f9.patchPatch
9b29abf9-4ab0-4765-b253-1875cd9b441ehttps://metacpan.org/release/TIMLEGGE/Net-SAML2-0.86/changesRelease Notes
Impacted products
Vendor Product Version
timlegge net\ \
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://cpan.org/modules",
          "defaultStatus": "unaffected",
          "packageName": "Net-SAML2",
          "product": "Net::SAML2",
          "programFiles": [
            "lib/Net/SAML2/Protocol/Assertion.pm",
            "lib/Net/SAML2/Binding/POST.pm"
          ],
          "programRoutines": [
            {
              "name": "Net::SAML2::Protocol::Assertion::new_from_xml"
            },
            {
              "name": "Net::SAML2::Binding::POST::handle_response"
            }
          ],
          "repo": "https://github.com/perl-net-saml2/perl-Net-SAML2",
          "vendor": "TIMLEGGE",
          "versions": [
            {
              "lessThan": "0.86",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:timlegge:net\\:\\:saml2:*:*:*:*:*:perl:*:*",
              "matchCriteriaId": "69FF1709-62F7-4E8C-B90D-ABFA96B07FF1",
              "versionEndExcluding": "0.86",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Net::SAML2 versions before 0.86 for Perl allow SAML authentication bypass via XML signature wrapping because new_from_xml reads assertion identity with document-wide XPath instead of the signed subtree.\n\nnew_from_xml reads the NameID, attribute values, SessionIndex, audience and other identity fields with document-wide XPath, such as //saml:Assertion/saml:AttributeStatement/saml:Attribute and //saml:Subject/saml:NameID, which select the first matching element in document order rather than the element covered by the verified signature. handle_response confirms that a signature is present and, when a cacert is configured, that it chains to the CA, but XML::Sig verifies only the element named by the signature\u0027s Reference URI, so unsigned sibling assertions in the same document are not covered. An attacker who holds any one IdP-signed assertion can add an unsigned attacker-authored assertion earlier in document order; the signature still verifies and the document-order XPath returns the attacker\u0027s NameID and attributes.\n\nAny caller that passes an untrusted Response to new_from_xml can accept identity fields from an assertion the IdP never signed, even when a cacert trust anchor is configured, so a party holding one valid IdP-signed assertion can authenticate as an arbitrary user."
    },
    {
      "lang": "es",
      "value": "Las versiones de Net::SAML2 anteriores a la 0.86 para Perl permiten la omisi\u00f3n de autenticaci\u00f3n SAML mediante la envoltura de firma XML porque new_from_xml lee la identidad de la aserci\u00f3n con XPath a nivel de documento en lugar del sub\u00e1rbol firmado.\n\nnew_from_xml lee el NameID, los valores de atributos, SessionIndex, la audiencia y otros campos de identidad con XPath a nivel de documento, como //saml:Assertion/saml:AttributeStatement/saml:Attribute y //saml:Subject/saml:NameID, que seleccionan el primer elemento coincidente en el orden del documento en lugar del elemento cubierto por la firma verificada. handle_response confirma que una firma est\u00e1 presente y, cuando se configura un cacert, que encadena a la CA, pero XML::Sig verifica solo el elemento nombrado por la URI de referencia de la firma, por lo que las aserciones hermanas sin firmar en el mismo documento no est\u00e1n cubiertas. Un atacante que posee cualquier aserci\u00f3n firmada por el IdP puede a\u00f1adir una aserci\u00f3n sin firmar, creada por el atacante, antes en el orden del documento; la firma a\u00fan se verifica y el XPath en orden de documento devuelve el NameID y los atributos del atacante.\n\nCualquier llamador que pasa una Respuesta no confiable a new_from_xml puede aceptar campos de identidad de una aserci\u00f3n que el IdP nunca firm\u00f3, incluso cuando se configura un ancla de confianza cacert, por lo que una parte que posee una aserci\u00f3n v\u00e1lida firmada por el IdP puede autenticarse como un usuario arbitrario."
    }
  ],
  "id": "CVE-2026-18092",
  "lastModified": "2026-10-23T21:10:00.157",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 8.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.2,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-18092",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-03T20:00:23.033425Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-03T14:16:25.030",
  "references": [
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "tags": [
        "Patch"
      ],
      "url": "https://github.com/perl-net-saml2/perl-Net-SAML2/commit/201fead7f42b83f40c84bf4a311a25b09acd18f9.patch"
    },
    {
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "tags": [
        "Release Notes"
      ],
      "url": "https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.86/changes"
    }
  ],
  "sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-347"
        }
      ],
      "source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
      "type": "Secondary"
    }
  ]
}



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