{"id":"CVE-2026-18092","state":"PUBLISHED","title":"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","description":"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'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.\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.","publishedAt":"2026-08-03T13:24:52.137Z","updatedAt":"2026-08-03T20:01:20.742Z","severity":{"score":8.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H","source":"CISA-ADP"},"assigner":"CPANSec","products":["TIMLEGGE Net::SAML2"],"affected":[{"vendor":"TIMLEGGE","product":"Net::SAML2","packageName":"Net-SAML2","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"0.86","versionType":"custom"}],"collectionURL":"https://cpan.org/modules","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"}],"references":["https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.86/changes","https://github.com/perl-net-saml2/perl-Net-SAML2/commit/201fead7f42b83f40c84bf4a311a25b09acd18f9.patch"],"weaknesses":["CWE-347"],"ingestedAt":"2026-10-29T20:11:10.572Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/18xxx/CVE-2026-18092.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-18092","state":"PUBLISHED","datePublished":"2026-08-03T13:24:52.137Z","dateUpdated":"2026-08-03T20:01:20.742Z","assignerShortName":"CPANSec","assignerOrgId":"9b29abf9-4ab0-4765-b253-1875cd9b441e","dateReserved":"2026-07-28T16:46:56.926Z"},"containers":{"cna":{"title":"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","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'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.\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."}],"affected":[{"vendor":"TIMLEGGE","product":"Net::SAML2","packageName":"Net-SAML2","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"0.86","versionType":"custom"}],"collectionURL":"https://cpan.org/modules","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"}],"references":[{"url":"https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.86/changes","tags":["release-notes"]},{"url":"https://github.com/perl-net-saml2/perl-Net-SAML2/commit/201fead7f42b83f40c84bf4a311a25b09acd18f9.patch","tags":["patch"]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-347","description":"CWE-347 Improper Verification of Cryptographic Signature","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"CPANSec","orgId":"9b29abf9-4ab0-4765-b253-1875cd9b441e","dateUpdated":"2026-08-03T13:24:52.137Z"},"impacts":[{"capecId":"CAPEC-115","descriptions":[{"lang":"en","value":"CAPEC-115 Authentication Bypass"}]}],"solutions":[{"lang":"en","value":"Upgrade to Net::SAML2 0.86 or later, which anchors identity extraction at the assertion subtree covered by a signature that validates against the configured trust anchor."}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"cpansec-cna-tool 0.1"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":8.1,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H","integrityImpact":"HIGH","userInteraction":"REQUIRED","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-08-03T20:00:23.033425Z","id":"CVE-2026-18092","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-03T20:01:20.742Z"}}]}}}