SAML Authentication Bypass in Net::SAML2 for Perl

CVE-2026-18089

What is CVE-2026-18089?

The vulnerability in Net::SAML2 versions prior to 0.86 allows an attacker to bypass SAML authentication. This occurs when the library verifies responses against the embedded certificate without a configured trust anchor, leading to the acceptance of forged assertions. Specifically, the verify_xml function, when invoked without specified trust anchors or a certificate authority, will improperly validate an XML signature derived from an attacker's self-signed certificate. This can allow unauthorized access due to insecure handling of authentication responses.

References