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step-ca Has Improper Authorization Check for SSH Certificate Revocation

Moderate severity GitHub Reviewed Published Dec 3, 2025 in smallstep/certificates • Updated Dec 4, 2025

Package

gomod github.com/smallstep/certificates (Go)

Affected versions

<= 0.28.4

Patched versions

0.29.0

Description

Summary

A security fix is now available for Step CA that resolves a vulnerability affecting deployments configured with the SSHPOP provisioner.
All operators running these provisioners should upgrade to the latest release (v0.29.0) immediately.

The issue was discovered and responsibly disclosed by a research team during a security review. There is no evidence of active exploitation.

To limit exploitation risk during a coordinated disclosure window, we are withholding detailed technical information for now. A full write-up will be published in several weeks.

Embargo List

If your organization runs Step CA in production and would like advance, embargoed notification of future security updates, visit https://u.step.sm/disclosure to request inclusion on our embargo list.

Acknowledgements

This issue was identified and reported by Gabriel Departout and Andy Russon, from AMOSSYS. This audit was sponsored by ANSSI (French Cybersecurity Agency) based on their Open-Source security audit program.

Stay safe, and thank you for helping us keep the ecosystem secure.

References

@dopey dopey published to smallstep/certificates Dec 3, 2025
Published to the GitHub Advisory Database Dec 3, 2025
Reviewed Dec 3, 2025
Published by the National Vulnerability Database Dec 3, 2025
Last updated Dec 4, 2025

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H

EPSS score

Weaknesses

Improper Authorization

The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Learn more on MITRE.

Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions. Learn more on MITRE.

CVE ID

CVE-2025-66406

GHSA ID

GHSA-j7c9-79x7-8hpr

Source code

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