How severe is CVE-2025-66567?

CVE-2025-66567 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-2025-66567 being actively exploited?

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

What products are affected by CVE-2025-66567?

CVE-2025-66567 affects Onelogin Ruby-saml. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-66567?

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-2025-66567 have an EU (EUVD) identifier?

Yes. CVE-2025-66567 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201812.

When was CVE-2025-66567 published?

CVE-2025-66567 was published on 2025-12-09 and last updated on 2026-06-17.

CVE-2025-66567

CVE-2025-66567 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% (30th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201812
Weakness: CWE-347
Affected product: Onelogin Ruby-saml
Published: 2025-12-09
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2025-66567?: 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.
How severe is CVE-2025-66567?: CVE-2025-66567 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-2025-66567 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-66567?: CVE-2025-66567 affects Onelogin Ruby-saml. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-66567?: 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-2025-66567 have an EU (EUVD) identifier?: Yes. CVE-2025-66567 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201812.
When was CVE-2025-66567 published?: CVE-2025-66567 was published on 2025-12-09 and last updated on 2026-06-17.

References

Affected products (1)

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

More vulnerabilities in Onelogin Ruby-saml

CVE-2024-45409 — Critical (CVSS 10.0): The Ruby SAML library is for implementing the client side of a SAML authorization. Ruby-SAML in <= 12.2 and 1.13.0 <=…
CVE-2025-25292 — Critical (CVSS 9.8): ruby-saml provides security assertion markup language (SAML) single sign-on (SSO) for Ruby. An authentication bypass…
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CVE-2025-66568 — Critical (CVSS 9.1): The ruby-saml library implements the client side of an SAML authorization. Versions up to and including 1.12.4, are…
CVE-2017-11428 — High (CVSS 7.7): OneLogin Ruby-SAML 1.6.0 and earlier may incorrectly utilize the results of XML DOM traversal and canonicalization APIs…

All CVEs affecting Onelogin Ruby-saml →

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