Fleet doesn’t validate a server’s certificate when connecting through SSH

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2025-23390: 0.19% estimated exploitation activity in the next 30 days; percentile 8.78 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact A vulnerability has been identified within Fleet where, by default, Fleet will automatically trust a remote server’s certificate when connecting through SSH if the certificate isn’t set in the knownhosts file. This could allow the execution of a man-in-the-middle (MitM) attack against Fleet. In case the server that is being connected to has a trusted entry in the knownhosts file, then Fleet will correctly check the authenticity of the presented certificate. Please consult the associated MITRE ATT&CK - Technique - Adversary-in-the-Middle for further information about this category of attack. Patches Patched versions include releases v0.10.12, v0.11.7 and v0.12.2. The fix involves some key areas with the following changes: - Git latest commit fetcher sources knownhosts entries from the following locations, in decreasing order of priority: 1. Secret referenced in a GitRepo’s clientSecretName field; 2. If no secret is referenced, in a gitcredential secret located in the GitRepo’s…

Published by the source

25 Apr 2025, 15:11 UTC

Last modified by the source

5 May 2025, 22:00 UTC

Source last checked

26 Oct 2026, 15:09 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xgpc-q899-67p8

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# Patch Next advisory brief: CVE-2025-23390

Advisory: Fleet doesn’t validate a server’s certificate when connecting through SSH
IDs: CVE-2025-23390, GHSA-xgpc-q899-67p8
Record: https://patchnext.com/advisories/cve-2025-23390 (revision 1, source checked 26 Oct 2026, 15:09 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/rancher/fleet 0.12.2, 0.11.7, 0.10.12. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/rancher/fleet: affected >= 0.9.0-rc.1, < 0.10.12; >= 0.11.0, < 0.11.7; >= 0.12.0, < 0.12.2; fixed in 0.11.7, 0.10.12, 0.12.2

## Suggested inspection (read-only)
- Go github.com/rancher/fleet: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/rancher/fleet.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-xgpc-q899-67p8 (GitHub-reviewed advisory GHSA-xgpc-q899-67p8 lists affected ranges: Go github.com/rancher/fleet >=0.9.0-rc.1 =0.11.0 =0.12.0 <0.12.2)

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