CVE-2025-66406: smallstep certificates · Incorrect Authorization
Affects smallstep certificatesSource CVE Database V5
Not known to be exploited · CVSS 5.0 Medium : upgrade to 0.29.0 when convenient.
Data as of 26 Oct 2026, 09:15 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.29.0
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:HExploitation evidence
Disclosed: evidence found.
CVE published 3 Dec 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade smallstep/certificates to 0.29.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
GitHubsmallstep/certificatespkg:github/smallstep/certificatesOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
European organizations should immediately upgrade Step CA to version 0.29.0 or later to remediate the improper authorization vulnerability. Until patching is complete, restrict access to the Step CA management interfaces and SSHPOP provisioner to trusted administrators only, minimizing the risk of privilege misuse. Implement strict role-based access controls (RBAC) and monitor logs for unusual certificate revocation activities. Conduct audits of SSH certificate revocation events to detect unauthorized actions promptly. Additionally, consider deploying network segmentation to isolate certificate management infrastructure from general user networks. Employ multi-factor authentication (MFA) for privileged accounts managing Step CA to reduce the risk of credential compromise. Finally, maintain an incident response plan that includes steps for rapid certificate re-issuance and recovery in case of unauthorized revocation.
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.