sshnet SSH.NET up to 2025.1.0 ScpClient ScpClient.Download directoryName/directoryInfo path traversal

Summaryinfo

A vulnerability categorized as critical has been discovered in sshnet SSH.NET up to 2025.1.0. The impacted element is the function ScpClient.Download of the component ScpClient. The manipulation of the argument directoryName/directoryInfo results in path traversal. This vulnerability was named CVE-2026-48798. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability, which was classified as critical, was found in sshnet SSH.NET up to 2025.1.0. Affected is the function ScpClient.Download of the component ScpClient. The manipulation of the argument directoryName/directoryInfo with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. This is going to have an impact on integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-48798 since 05/22/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1006.

Upgrading to version 2026.0.0 eliminates this vulnerability.

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Productinfo

Type

• SSH Server Software

Vendor

• sshnet

Name

• SSH.NET

Version

• 2025.0
• 2025.1.0

Website

• Product: https://github.com/sshnet/SSH.NET/

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