EUVD-2026-52266
GHSA-p5j9-p2w8-q5rw
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
SAML ACS endpoints are public-facing and unauthenticated by design; no confidentiality or availability impact - only integrity via identity forgery.
Primary rating from Vendor (CPANSec).
CVSS VectorVendor: CPANSec
Lifecycle Timeline
5DescriptionCVE.org
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.
AnalysisAI
SAML authentication bypass in Net::SAML2 versions before 0.86 for Perl allows remote unauthenticated attackers to forge arbitrary SAML assertions against service providers that omit a trust anchor during library configuration. The flaw is in verify_xml, which exits early after validating the XML signature against the certificate embedded within the response itself - meaning an attacker who controls the response can supply their own self-signed certificate and sign any assertion they choose. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that the target Perl application constructs Binding::POST or calls Assertion->new_from_xml without supplying a cacert, cert_text, or anchors argument - meaning no trust anchor is configured for SAML signature validation. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The provided CVSS 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N) accurately reflects the threat model for vulnerable deployments: network-reachable SAML assertion consumer service endpoints are public-facing by design, exploitation requires no authentication, and attack complexity is low because no special conditions beyond reaching the endpoint are needed. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Upgrade Net::SAML2 to version 0.86 or later immediately; the changelog confirming the fix is at https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.88/source/Changes - upgrading to the latest available release (0.88 at time of writing) is safest, as fixes may have been applied incrementally across 0.86-0.88. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all systems and applications using Net::SAML2 Perl library by checking package managers and dependency manifests. …
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External POC / Exploit Code
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