How severe is CVE-2025-66568?

CVE-2025-66568 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2025-66568 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-66568?

CVE-2025-66568 affects Onelogin Ruby-saml. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-66568?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2025-66568 have an EU (EUVD) identifier?

Yes. CVE-2025-66568 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201828.

When was CVE-2025-66568 published?

CVE-2025-66568 was published on 2025-12-09 and last updated on 2026-06-17.

CVE-2025-66568

CVE-2025-66568 is a critical-severity vulnerability in Onelogin Ruby-saml with a CVSS 3.x base score of 9.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
CVSS v4: 9.3
EPSS exploit prediction: 0% (11th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201828
Weakness: CWE-347
Affected product: Onelogin Ruby-saml
Published: 2025-12-09
Last modified: 2026-06-17

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.

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.
How severe is CVE-2025-66568?: CVE-2025-66568 has a CVSS 3.x base score of 9.1, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2025-66568 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66568?: CVE-2025-66568 affects Onelogin Ruby-saml. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-66568?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2025-66568 have an EU (EUVD) identifier?: Yes. CVE-2025-66568 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201828.
When was CVE-2025-66568 published?: CVE-2025-66568 was published on 2025-12-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:onelogin:ruby-saml:*:*:*:*:*:*:*:*

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