{"id":"CVE-2026-18089","state":"PUBLISHED","title":"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","description":"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.","publishedAt":"2026-08-03T12:42:08.879Z","updatedAt":"2026-08-03T19:56:33.033Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","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/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"}],"references":["https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.88/source/Changes","https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Role/VerifyXML.pm#L32","https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Binding/POST.pm#L21","https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Protocol/Assertion.pm#L84"],"weaknesses":["CWE-347","CWE-295"],"ingestedAt":"2026-10-29T20:11:10.572Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/18xxx/CVE-2026-18089.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-18089","state":"PUBLISHED","datePublished":"2026-08-03T12:42:08.879Z","dateUpdated":"2026-08-03T19:56:33.033Z","assignerShortName":"CPANSec","assignerOrgId":"9b29abf9-4ab0-4765-b253-1875cd9b441e","dateReserved":"2026-07-28T16:26:10.967Z"},"containers":{"cna":{"title":"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","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."}],"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/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"}],"references":[{"url":"https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.88/source/Changes","tags":["release-notes"]},{"url":"https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Role/VerifyXML.pm#L32"},{"url":"https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Binding/POST.pm#L21"},{"url":"https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Protocol/Assertion.pm#L84"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-347","description":"CWE-347 Improper Verification of Cryptographic Signature","lang":"en","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-295","description":"CWE-295 Improper Certificate Validation","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"CPANSec","orgId":"9b29abf9-4ab0-4765-b253-1875cd9b441e","dateUpdated":"2026-08-03T12:42:08.879Z"},"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 requires a cacert or cert_text trust anchor before a response or assertion signature is verified."}],"source":{"discovery":"UNKNOWN"},"timeline":[{"lang":"en","time":"2026-07-31T00:00:00.000Z","value":"Version 0.86 released with fix."},{"lang":"en","time":"2026-07-31T00:00:00.000Z","value":"Version 0.88 released, re-issuing 0.86 with a corrected version number."}],"workarounds":[{"lang":"en","value":"For deployments that cannot upgrade, construct Net::SAML2::Binding::POST, and call Net::SAML2::Protocol::Assertion->new_from_xml, with a cacert, cert_text, or anchors argument identifying the IdP signing certificate."}],"x_generator":{"engine":"cpansec-cna-tool 0.1"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.5,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","integrityImpact":"HIGH","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"NONE","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-08-03T19:56:09.872860Z","id":"CVE-2026-18089","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-03T19:56:33.033Z"}}]}}}