# CVE-2026-85756: SSH.NET: ScpClient allows server-side RCE via default SCP path handling

> Attacker-controlled paths in SSH.NET ScpClient can execute commands on shell-based servers due to insufficient quoting, requiring an upgrade to fix.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 16 Sep 2026
- **Updated:** 16 Sep 2026
- **Also known as:** GHSA-mggc-4xg6-vcxf

## What is CVE-2026-85756?

CVE-2026-85756 is a high-severity command injection vulnerability in sshnet SSH.NET, published on 16 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

SSH.NET is a Secure Shell (SSH) library for .NET. Prior to 2026.0.0, ScpClient places caller-supplied remote paths into the command used to run scp on the server, and the default RemotePathTransformation.DoubleQuote transformation cannot safely quote every remote command interpreter. When an application passes an attacker-controlled path to a shell-based server, shell metacharacters not neutralized by the active IRemotePathTransformation can execute commands as the authenticated SSH user. Exploitation requires a shell-based server and a path crafted for that shell's parsing rules; non-shell servers and paths fully neutralized by the selected transformation are not affected. RemotePathTransformation.ShellQuote is available for POSIX shells, while SftpClient avoids a remote shell entirely. This issue is fixed in version 2026.0.0.

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2026-85756?

2 open source packages ship an affected version, including SSH.NET.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `SSH.NET` | NuGet | All versions | 2026.0.0 |
| `SSH.NET` | NuGet | All versions | 2026.0.0 |

## How do I fix CVE-2026-85756?

Upgrade SSH.NET to 2026.0.0 or later.

## Is CVE-2026-85756 being exploited?

There is no known exploitation of CVE-2026-85756 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-85756 and fix it if it is affected.

What it is: CVE-2026-85756 is a high-severity command injection vulnerability in sshnet SSH.NET, published on 16 Sep 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-2026-85756 in the wild and no public exploit code.

Affected packages and fixed versions:
- SSH.NET (NuGet): affected all versions; fixed in 2026.0.0
- SSH.NET (NuGet): affected all versions; fixed in 2026.0.0

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-2026-85756/ (Markdown: https://insights.sbomify.com/CVE-2026-85756/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-85756
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-85756
- OSV: https://osv.dev/vulnerability/CVE-2026-85756

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-85756/
Summaries are generated and may contain mistakes; the official description above is the record.