CVE-2026-18092Network attack vector

Authentication bypass via XML signature wrapping

Published Aug 3, 2026 · Updated Aug 3, 2026

XML signature wrapping in Net::SAML2 before 0.86 allows remote attackers to authenticate as arbitrary users via crafted SAML responses. Net::SAML2::Protocol::Assertion::new_from_xml uses document-wide XPath to read identity fields from the first assertion rather than the subtree validated by XML::Sig. Remote attackers must possess an IdP-signed assertion; an unsigned sibling assertion can then supply arbitrary NameID and attributes.

CVSS severity8.1
High
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

XML signature wrapping in Net::SAML2 before 0.86 allows remote attackers to authenticate as arbitrary users via crafted SAML responses. Net::SAML2::Protocol::Assertion::new_from_xml uses document-wide XPath to read identity fields from the first assertion rather than the subtree validated by XML::Sig. Remote attackers must possess an IdP-signed assertion; an unsigned sibling assertion can then supply arbitrary NameID and attributes.

The record

CVE
CVE-2026-18092
Published
Aug 3, 2026
Updated
Aug 3, 2026
Vendor
Timothy Legge
Product
Net::SAML2
Classifications
CWE-347, CAPEC-115, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=0 <0.86

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Timothy Legge · Net::SAML2version=0 <0.86

Published CVSS scores

8.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
CAPEC-115Authentication Bypass
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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