EUVD-2026-52291
GHSA-657v-xpf8-79x2
Severity by source
AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
Authentication bypass gives full access to victim account data (C:H); no crash or DoS path is described (A:N); attacker needs any IdP assertion but no SP credentials (PR:N, AC:L).
Primary rating from Vendor (CPANSec).
CVSS VectorVendor: CPANSec
Lifecycle Timeline
5DescriptionCVE.org
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.
AnalysisAI
XML Signature Wrapping in Net::SAML2 before 0.86 allows any party holding a single valid IdP-signed assertion to authenticate as an arbitrary user against Perl applications that use this SAML SP library. Identity fields - NameID, attributes, SessionIndex, audience - are extracted via document-wide XPath queries selecting the first matching element in document order, not the element covered by the verified signature; an attacker who prepends an unsigned forged assertion to a Response containing their own legitimate signed assertion bypasses identity verification entirely while the signature check still passes. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The attacker must possess at least one valid SAML assertion issued and signed by the target Identity Provider - this may be an assertion for any account, including a low-privilege or self-registered one, but purely external parties who cannot obtain any IdP-signed assertion cannot exploit this flaw. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The NVD CVSS 8.1 vector (AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H) contains two metrics that conflict with the described impact and warrant explicit scrutiny. … 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 via CPAN (`cpanm Net::SAML2` or `cpan -i Net::SAML2`). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all Perl applications and systems using Net::SAML2 and confirm current versions in use. …
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External POC / Exploit Code
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