FKIE_CVE-2026-18089
Vulnerability from fkie_nvd - Published: 2026-08-03 14:16 - Updated: 2026-08-03 20:17
Severity
Summary
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 $cacert;".
Any caller that constructs Binding::POST or calls Assertion->new_from_xml without a cacert, cert_text, or anchors argument accepts a response signed by an attacker generated key whose self-signed certificate is embedded in that response, authenticating an arbitrary assertion.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"collectionURL": "https://cpan.org/modules",
"defaultStatus": "unaffected",
"packageName": "Net-SAML2",
"product": "Net::SAML2",
"programFiles": [
"lib/Net/SAML2/Role/VerifyXML.pm",
"lib/Net/SAML2/Binding/POST.pm",
"lib/Net/SAML2/Protocol/Assertion.pm"
],
"programRoutines": [
{
"name": "Net::SAML2::Role::VerifyXML::verify_xml"
},
{
"name": "Net::SAML2::Binding::POST::handle_response"
},
{
"name": "Net::SAML2::Protocol::Assertion::_verify_encrypted_assertion"
}
],
"repo": "https://github.com/perl-net-saml2/perl-Net-SAML2",
"vendor": "TIMLEGGE",
"versions": [
{
"lessThan": "0.86",
"status": "affected",
"version": "0",
"versionType": "custom"
}
]
}
],
"source": "9b29abf9-4ab0-4765-b253-1875cd9b441e"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Net::SAML2 versions before 0.86 for Perl allow SAML authentication bypass by verifying responses against the response-embedded certificate in verify_xml when no trust anchor is configured.\n\nverify_xml in Net::SAML2::Role::VerifyXML runs \"return if !$anchors \u0026\u0026 !$cacert;\" as soon as the XML::Sig check succeeds, and that check uses the X.509 certificate taken from the response\u0027s 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;\".\n\nAny caller that constructs Binding::POST or calls Assertion-\u003enew_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."
}
],
"id": "CVE-2026-18089",
"lastModified": "2026-08-03T20:17:14.203",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 7.5,
"baseSeverity": "HIGH",
"confidentialityImpact": "NONE",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 3.6,
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-18089",
"options": [
{
"exploitation": "none"
},
{
"automatable": "yes"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-03T19:56:09.872860Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-08-03T14:16:24.890",
"references": [
{
"source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
"url": "https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Binding/POST.pm#L21"
},
{
"source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
"url": "https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Protocol/Assertion.pm#L84"
},
{
"source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
"url": "https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.85/source/lib/Net/SAML2/Role/VerifyXML.pm#L32"
},
{
"source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
"url": "https://metacpan.org/release/TIMLEGGE/Net-SAML2-0.88/source/Changes"
}
],
"sourceIdentifier": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
"vulnStatus": "Awaiting Analysis",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-295"
},
{
"lang": "en",
"value": "CWE-347"
}
],
"source": "9b29abf9-4ab0-4765-b253-1875cd9b441e",
"type": "Secondary"
}
]
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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