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CVE-2025-66568

Onelogin Ruby-saml authentication bypass

9.1 CRITICALEPSS 0.23%
  1. Published9 Dec 2025

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.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

Onelogin Ruby-saml< 1.18.0

Remediation

Fixed in
Onelogin Ruby-saml≥ 1.18.0

References

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Frequently asked

Is CVE-2025-66568 being actively exploited?

CVE-2025-66568 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.23%.

How severe is CVE-2025-66568?

CVE-2025-66568 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.23% probability of exploitation.

Which products are affected by CVE-2025-66568?

Affected products include Onelogin Ruby-saml.

How do I fix CVE-2025-66568?

Upgrade affected software to a fixed version, for example Onelogin Ruby-saml 1.18.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.