EUVD-2025-201014Published

Improper Authorization Check for SSH Certificate Revocation

Collected exploitation and prediction evidence

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

cve-program · CVE-2025-66406

Published

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.

Source published: 3 Dec 2025 19:13:48 UTC
Source modified: 3 Dec 2025 21:40:59 UTC
Observed here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

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CVSS 3.1 · 5.0 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H

euvd · EUVD-2025-201014

Published

EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

Original publisher date fields

datePublished: Dec 3, 2025, 7:13:48 PM

dateUpdated: Dec 3, 2025, 9:40:59 PM

Source published: Dec 3, 2025, 7:13:48 PM (timezone not stated)
Source modified: Dec 3, 2025, 9:40:59 PM (timezone not stated)
Observed here: 7 Nov 2026 05:38:00 UTC
Source terms: ENISA EUVD · source terms and attribution apply

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EUVD CVSS 3.1 · 5.0 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H

nvd · CVE-2025-66406

Published

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Deferred

Weakness classifications: CWE-863

Original publisher date fields

published: 2025-12-03T20:16:26.560

lastModified: 2026-10-18T17:10:00.110

Source published: 3 Dec 2025 20:16:26 UTC
Source modified: 18 Oct 2026 17:10:00 UTC
Observed here: 25 Oct 2026 03:17:36 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

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CVSS 3.1 · [email protected] · Secondary · 5.0 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H

osv · GHSA-j7c9-79x7-8hpr

Published

## Summary An authorized attacker can bypass authorization checks and revoke any SSH certificate issued by Step CA by using a valid revocation token. ## Details Step CA users can obtain SSH certificates from a few provisioners. The SSHPOP provisioner allows revocation of the SSH certificate (preventing future certificate renewals) using a token. Due to a missing validity check, this token could be used to revoke any SSH certificate issued by the CA. To create a token, an attacker must have access to the CA endpoint and a valid SSH certificate, meaning they were already authorized to obtain an SSH certificate. The attacker must also know the serial number of the certificate they want to revoke. ## Impact There is no way to mitigate this attack. It is recommended to update to v0.29.0 or newer. ## Fix In v0.29.0, the token validation logic was strengthened to bind each token to a specific SSH certificate serial number. ## Acknowledgements This issue was identified and reported by Gabriel Departout and Andy Russon, from [AMOSSYS](http://amossys.fr/). This audit was sponsored by [ANSSI](https://cyber.gouv.fr/) (French Cybersecurity Agency) based on [their Open-Source security audit program](https://cyber.gouv.fr/open-source-lanssi#:~:text=Financement%20d%27%C3%A9valuations%20de%20s%C3%A9curit%C3%A9%20de%20logiciels%20libres). ## 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. Stay safe, and thank you for helping us keep the ecosystem secure.

Source published: 3 Dec 2025 16:27:59 UTC
Source modified: 10 Sep 2026 03:50:31 UTC
Observed here: 24 Oct 2026 13:19:41 UTC
Source terms: GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:L/A:H

Publisher rating · MODERATE

osv · GO-2025-4181

Published

step-ca Has Improper Authorization Check for SSH Certificate Revocation in github.com/smallstep/certificates

Source published: 8 Dec 2025 21:31:36 UTC
Source modified: 4 Feb 2026 03:17:38 UTC
Observed here: 24 Oct 2026 13:19:41 UTC
Source terms: OSV · upstream source license applies

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