How severe is CVE-2025-66406?

CVE-2025-66406 has a CVSS 3.x base score of 5.0, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.

Is CVE-2025-66406 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2025-66406?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-66406 have an EU (EUVD) identifier?

Yes. CVE-2025-66406 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201014.

When was CVE-2025-66406 published?

CVE-2025-66406 was published on 2025-12-03 and last updated on 2026-06-17.

CVE-2025-66406

CVE-2025-66406 is a medium-severity vulnerability with a CVSS 3.x base score of 5.0. 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-863.

Key facts

Severity: Medium (CVSS 3.x base score 5.0)
EPSS exploit prediction: 0% (4th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-201014
Weakness: CWE-863
Published: 2025-12-03
Last modified: 2026-06-17

Description

Step CA is an online certificate authority for secure, automated certificate management for DevOps. Prior to 0.29.0, there is an improper authorization check for SSH certificate revocation. This affects deployments configured with the SSHPOP provisioner. This vulnerability is fixed in 0.29.0.

Frequently asked questions

What is CVE-2025-66406?: Step CA is an online certificate authority for secure, automated certificate management for DevOps. Prior to 0.29.0, there is an improper authorization check for SSH certificate revocation. This affects deployments configured with the SSHPOP provisioner. This vulnerability is fixed in 0.29.0.
How severe is CVE-2025-66406?: CVE-2025-66406 has a CVSS 3.x base score of 5.0, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.
Is CVE-2025-66406 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (4th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2025-66406?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-66406 have an EU (EUVD) identifier?: Yes. CVE-2025-66406 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-201014.
When was CVE-2025-66406 published?: CVE-2025-66406 was published on 2025-12-03 and last updated on 2026-06-17.

References

https://github.com/smallstep/certificates/security/advisories/GHSA-j7c9-79x7-8hpr

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