CVE-2025-66406 Improper Authorization Check for SSH Certificate Revocation
Attackers can bypass authorization checks to revoke SSH certificates in Step CA deployments using the SSHPOP provisioner.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-66406?
CVE-2025-66406 is a medium-severity missing authorization vulnerability in smallstep certificates, published on 3 Dec 2025. An attacker needs administrator access to exploit it, with no action from the victim.
Official 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.
Weakness: CWE-863
Which versions are affected by CVE-2025-66406?
3 open source packages ship an affected version, including github.com/smallstep/certificates.
| Package | Affected | Fixed in |
|---|---|---|
github.com/smallstep/certificates Go | All versions | 0.29.0 |
github.com/smallstep/certificates Go | All versions | 0.29.0 |
github.com/smallstep/certificates Go | All versions | 0.29.0 |
How do I fix CVE-2025-66406?
Upgrade github.com/smallstep/certificates to 0.29.0 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2025-66406 being exploited?
There is no known exploitation of CVE-2025-66406 in the wild and no public exploit code.
Sources
Also known as CLEANSTART-2026-MK81849, CLEANSTART-2026-RS62088, GHSA-j7c9-79x7-8hpr, GO-2025-4181, MINI-xmrj-xrj8-ffh8.