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CVE-2026-18089 Detail

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. 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.


Metrics

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CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

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URL Source(s) Tag(s)
CPANSec
CPANSec
CPANSec
CPANSec

Weakness Enumeration

CWE-ID CWE Name Source
CWE-295 Improper Certificate Validation CPANSec  
CWE-347 Improper Verification of Cryptographic Signature CPANSec  

Change History

2 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-18089
NVD Published Date:
08/03/2026
NVD Last Modified:
08/03/2026
Source:
CPANSec