CVE-2026-18089
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.
Affected Products
-
CVE record
-
NVD configurations
-
Red Hat packages
No data
-
OpenCVE enrichment
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| TIMLEGGE | Net::SAML2 | unaffected |
|
No data.
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Timlegge | Net::saml2 |
|
Remediation
Vendor Solution
Upgrade to Net::SAML2 0.86 or later, which requires a cacert or cert_text trust anchor before a response or assertion signature is verified.
Vendor Workaround
For deployments that cannot upgrade, construct Net::SAML2::Binding::POST, and call Net::SAML2::Protocol::Assertion->new_from_xml, with a cacert, cert_text, or anchors argument identifying the IdP signing certificate.
Tracking
Advisories
Metrics
No CVSS v4.0
Attack Vector Network
Attack Complexity Low
Privileges Required None
Scope Unchanged
Confidentiality Impact None
Integrity Impact High
Availability Impact None
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.234% probability within 30 days)
Exploitation none
Automatable yes
Technical Impact partial
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
|
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Timlegge
Timlegge net::saml2 |
|
| Vendors & Products |
Timlegge
Timlegge net::saml2 |
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | 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 | |
| Weaknesses | CWE-295 CWE-347 |
|
| References |
|
|
