CVE-2025-66568: ruby-saml Signature Bypass — Fix

Description

The ruby-saml library implements the client side of an SAML authorization. Versions up to and including 1.12.4, are vulnerable to authentication bypass through the libxml2 canonicalization process used by Nokogiri for document transformation, which allows an attacker to execute a Signature Wrapping attack. When libxml2’s canonicalization is invoked on an invalid XML input, it may return an empty string rather than a canonicalized node. ruby-saml then proceeds to compute the DigestValue over this empty string, treating it as if canonicalization succeeded. This issue is fixed in version 1.18.0.

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CVSS v3.1 Score

9.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Weakness Type (CWE)

CWE-347 CWE-347

Affected Products

Vendor	Product	Versions
onelogin	ruby-saml	< 1.18.0

References

Advisories & Patches

https://github.com/SAML-Toolkits/ruby-saml/security/advisories/GHSA-x4h9-gwv3-r4m4

Other References

https://github.com/SAML-Toolkits/ruby-saml/commit/acac9e9cc0b9a507882c614f25d41f8b47be349a

Frequently Asked Questions

What is CVE-2025-66568? +

The ruby-saml library implements the client side of an SAML authorization. Versions up to and including 1.12.4, are vulnerable to authentication bypass through the libxml2 canonicalization process used by Nokogiri for document transformation, which allows an attacker to execute a Signature Wrapping attack. When libxml2’s canonicalization is invoked on an invalid XML input, it may return an empty string rather than a canonicalized node. ruby-saml then proceeds to compute the DigestValue over this empty string, treating it as if canonicalization succeeded. This issue is fixed in version 1.18.0. It has a CVSS v3.1 base score of 9.1 (CRITICAL).

How severe is CVE-2025-66568? +

CVE-2025-66568 has a CVSS v3.1 score of 9.1 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.

What products are affected by CVE-2025-66568? +

CVE-2025-66568 affects products from onelogin, specifically: ruby-saml. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-66568? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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