# CVE-2025-23390: Fleet doesn’t validate a server’s certificate when connecting through SSH

> Fleet fails to validate SSH server certificates by default, allowing man-in-the-middle attacks against connections.

- **Severity:** Medium 6.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Oct 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-xgpc-q899-67p8, GO-2025-3649

## What is CVE-2025-23390?

CVE-2025-23390 is a medium-severity vulnerability in SUSE fleet, published on 15 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

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 `known_hosts` 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 known_hosts file, then Fleet will correctly check the authenticity of the presented certificate.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2025-23390?

7 open source packages ship an affected version, including github.com/rancher/fleet.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/rancher/fleet` | Go | From 0.11.0 | 0.11.7 |
| `github.com/rancher/fleet` | Go | From 0.11.0 | 0.11.7 |
| `github.com/rancher/fleet` | Go | From 0.12.0 | 0.12.2 |
| `github.com/rancher/fleet` | Go | From 0.12.0 | 0.12.2 |
| `github.com/rancher/fleet` | Go | From 0.9.0-rc.1 | 0.10.12, 0.11.7, 0.12.2 |
| `github.com/rancher/fleet` | Go | From 0.9.0-rc.1 | 0.10.12 |
| `github.com/rancher/fleet` | Go | From 0.9.0-rc.1 | 0.10.12 |

## How do I fix CVE-2025-23390?

Upgrade github.com/rancher/fleet to a fixed version for your release line: 0.11.7, 0.12.2 or 0.10.12.

## Is CVE-2025-23390 being exploited?

There is no known exploitation of CVE-2025-23390 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-23390 and fix it if it is affected.

What it is: CVE-2025-23390 is a medium-severity vulnerability in SUSE fleet, published on 15 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-23390 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/rancher/fleet (Go): affected from 0.11.0; fixed in 0.11.7
- github.com/rancher/fleet (Go): affected from 0.11.0; fixed in 0.11.7
- github.com/rancher/fleet (Go): affected from 0.12.0; fixed in 0.12.2
- github.com/rancher/fleet (Go): affected from 0.12.0; fixed in 0.12.2
- github.com/rancher/fleet (Go): affected from 0.9.0-rc.1; fixed in 0.10.12, 0.11.7, 0.12.2
- github.com/rancher/fleet (Go): affected from 0.9.0-rc.1; fixed in 0.10.12
- github.com/rancher/fleet (Go): affected from 0.9.0-rc.1; fixed in 0.10.12

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-23390/ (Markdown: https://insights.sbomify.com/CVE-2025-23390/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-23390
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-23390
- OSV: https://osv.dev/vulnerability/CVE-2025-23390

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-23390/
Summaries are generated and may contain mistakes; the official description above is the record.