CVE-2026-18089
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk7th percentile - higher than 7% of all known CVEs
Summary
A vulnerability in the Net::SAML2 library for Perl (versions before 0.86) allows SAML authentication bypass by verifying responses against the response-embedded certificate when no trust anchor is configured. The verify_xml function accepts a response signed with an attacker's key, allowing authentication of an arbitrary assertion.
Risk Assessment
Organizations using Net::SAML2 without a configured CA certificate or trust anchor are at risk of accepting a forged SAML response and unauthorized authentication.
Recommendation
Configure a trust anchor (cacert, cert_text, or anchors) or update the Net::SAML2 library to version 0.86 or later.
Other vulnerabilities in Net::SAML2
See all- CVE-2026-18108Critical
A vulnerability in the Net::SAML2 library for Perl (versions before 0.86) allows SAML authentication bypass. The _verify_encrypted_assertion function accepts a decrypted assertion without a signature, enabling an attacker to send an unsigned assertion encrypted with the SP's certificate and authenticate as any user.
- CVE-2026-18092High
A vulnerability in the Net::SAML2 library for Perl (versions before 0.86) allows SAML authentication bypass via XML signature wrapping. The new_from_xml function reads assertion identity using document-wide XPath instead of the signed subtree, allowing an attacker to prepend an unsigned assertion and assume a user's identity.
Original NVD description (English source)
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. verify_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;". Any 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.