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Vulnerability Intelligence

CVE-2025-66567

CRITICAL9.3

ruby-saml has a SAML authentication bypass due to namespace handling (parser differential)

Published Dec 9, 2025

Modified 1 months ago

No fix available

Details

The ruby-saml library is for implementing the client side of a SAML authorization. ruby-saml versions up to and including 1.12.4 contain an authentication bypass vulnerability due to an incomplete fix for CVE-2025-25292. ReXML and Nokogiri parse XML differently, generating entirely different document structures from the same input. This allows an attacker to execute a Signature Wrapping attack. This issue is fixed in version 1.18.0.

References

WEBhttps://github.com/SAML-Toolkits/ruby-saml/commit/e9c1cdbd0f9afa467b585de279db0cbd0fb8ae97 WEBhttps://github.com/SAML-Toolkits/ruby-saml/security/advisories/GHSA-9v8j-x534-2fx3 WEBhttps://github.com/advisories/GHSA-754f-8gm6-c4r2 ADVISORYhttps://www.cve.org/CVERecord?id=CVE-2025-66567

CVSS Analysis

CVSS v4.0

9.3

Exploitability

Attack Vector

NetworkAV:N

Attack Complexity

LowAC:L

Attack Requirements

NoneAT:N

Privileges Required

NonePR:N

User Interaction

NoneUI:N

Vulnerable System

Vuln. Confidentiality

HighVC:H

Vuln. Integrity

HighVI:H

Vuln. Availability

NoneVA:N

Subsequent System

Subseq. Confidentiality

NoneSC:N

Subseq. Integrity

NoneSI:N

Subseq. Availability

NoneSA:N

9.3/CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Weakness Type (CWE)

Other

Ecosystems

Timeline

PublishedDec 9, 2025

ModifiedDec 9, 2025

CVE-2025-66567 | Mondoo Vulnerability Intelligence