========================================================================
CVE-2026-18092                                       CPAN Security Group
========================================================================

         CVE ID:  CVE-2026-18092
   Distribution:  Net-SAML2
       Versions:  before 0.86

       MetaCPAN:  https://metacpan.org/dist/Net-SAML2
       VCS Repo:  https://github.com/perl-net-saml2/perl-Net-SAML2

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.

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.

Problem types
-------------
- CWE-347 Improper Verification of Cryptographic Signature

Solutions
---------
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.

References
----------
https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.86/changes
https://github.com/perl-net-saml2/perl-Net-SAML2/commit/201fead7f42b83f40c84bf4a311a25b09acd18f9.patch