CVE-2026-48798
Received Received - Intake

SSH.NET Directory Traversal via SCP File Download

Publication date: 2026-08-18

Last updated on: 2026-08-18

Assigner: GitHub, Inc.

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.

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Meta Information

Published
2026-08-18
Last Modified
2026-08-18
Generated
2026-08-18
AI Q&A
2026-08-18
EPSS Evaluated
N/A
NVD
CVE-2026-48798
EUVD
EUVD-2026-60945

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
sshnet ssh.net to 2026.0.0 (exc)
sshnet ssh.net 2026.0.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
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.
CWE-73 The product allows user input to control or influence paths or file names that are used in filesystem operations.

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Executive Summary

This vulnerability affects the SSH.NET library versions up to 2025.1.0. It involves the ScpClient.Download method which does not properly validate file and directory names returned by a remote SCP server. Attackers can use path traversal sequences like ../ or absolute paths to write or overwrite files outside the intended download directory.

Detection Guidance

To detect this vulnerability, check if your system uses SSH.NET library versions 2025.1.0 or earlier. Inspect installed packages for SSH.NET and verify version numbers. Monitor network traffic for SCP downloads involving directory operations from untrusted servers.

Impact Analysis

An attacker could overwrite critical system files such as ~/.ssh/authorized_keys or shell configuration files. This may lead to privilege escalation, persistence on the system, or remote code execution. The attack requires the victim to initiate a directory download from a malicious server.

Mitigation Strategies

Upgrade SSH.NET to version 2026.0.0 or later immediately. Avoid downloading directories from untrusted SCP servers. If using directory downloads, validate all server responses before processing. Review system files for unauthorized changes after any SCP operations.

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