# CVE-2026-48798: SSH.NET: ScpClient Recursive Download Allows Arbitrary File Write via Server-Controlled SCP Filenames

> A malicious SSH server can exploit path traversal in SSH.NET's SCP client to write arbitrary files on the client system, potentially leading to code execution.

- **Severity:** High 7.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 18 Aug 2026
- **Updated:** 18 Aug 2026
- **Also known as:** GHSA-q939-rpr3-3284

## What is CVE-2026-48798?

CVE-2026-48798 is a high-severity path traversal vulnerability in sshnet SSH.NET, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

SSH.NET is a Secure Shell (SSH) library for .NET. In 2025.1.0 and earlier, ScpClient.Download(string directoryName, DirectoryInfo directoryInfo) trusts file and directory names returned by a remote SCP server and combines them with the requested local directory without containment validation, allowing a malicious, compromised, or man-in-the-middle server to use ../ sequences or absolute paths to create or overwrite files anywhere writable by the client process. This issue is fixed in version 2026.0.0.

Weakness: CWE-73 (External Control of File Name or Path), CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2026-48798?

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-2026-48798?

Upgrade SSH.NET to 2026.0.0 or later.

## Is CVE-2026-48798 being exploited?

There is no known exploitation of CVE-2026-48798 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48798 and fix it if it is affected.

What it is: CVE-2026-48798 is a high-severity path traversal vulnerability in sshnet SSH.NET, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-48798 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-2026-48798/ (Markdown: https://insights.sbomify.com/CVE-2026-48798/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48798
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48798
- OSV: https://osv.dev/vulnerability/CVE-2026-48798

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-48798/
Summaries are generated and may contain mistakes; the official description above is the record.