SSH.NET: ScpClient allows server-side RCE via default SCP path handling

Exploitation

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

CVSS

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

EPSS

• CVE-2026-85756: 0.62% estimated exploitation activity in the next 30 days; percentile 49.62 (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.

Summary Default SCP remote-path handling places caller-supplied paths into the command that runs scp on the server. On a shell-based server that command is interpreted by a shell, so an attacker-influenced path that is not quoted to suit that shell can execute as a command as the authenticated SSH user. SSH.NET provides ScpClient.RemotePathTransformation to control escaping behaviour (defaulting to RemotePathTransformation.DoubleQuote) but cannot guarantee safety for arbitrary remote command interpreters. This is inherent to running scp over a remote shell (cf. CVE-2020-15778). Impact Command execution on the SSH server as the authenticated SSH user, when an application passes an attacker-influenced remote path to ScpClient against a shell-based server. Exploitation depends on conditions beyond the attacker's control: the remote server must be shell-based, and the attacker-influenced path must be crafted to defeat the quoting applied by the transformation in effect — that is, to use…

Published by the source

17 Sep 2026, 17:18 UTC

Last modified by the source

17 Sep 2026, 17:30 UTC

Source last checked

26 Oct 2026, 17:05 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mggc-4xg6-vcxf

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-mggc-4xg6-vcxf

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# Patch Next advisory brief: CVE-2026-85756

Advisory: SSH.NET: ScpClient allows server-side RCE via default SCP path handling
IDs: CVE-2026-85756, GHSA-mggc-4xg6-vcxf
Record: https://patchnext.com/advisories/cve-2026-85756 (revision 2, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: ssh.net 2026.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet ssh.net: affected < 2026.0.0; fixed in 2026.0.0

## Suggested inspection (read-only)
- NuGet ssh.net: 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 ssh.net.
- 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://osv.dev/vulnerability/GHSA-mggc-4xg6-vcxf (OSV record GHSA-mggc-4xg6-vcxf lists affected ranges: NuGet ssh.net >=0 <2026.0.0 (fixed))
- Verified: https://github.com/advisories/GHSA-mggc-4xg6-vcxf (GitHub-reviewed advisory GHSA-mggc-4xg6-vcxf lists affected ranges: NuGet ssh.net >=0 <2026.0.0)

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