mark3labs Mcp-filesystem-server 0.11.1 Link Resolution helper.go validatePath path traversal

Summaryinfo

A vulnerability described as critical has been identified in mark3labs Mcp-filesystem-server 0.11.1. Impacted is the function validatePath of the file filesystemserver/handler/helper.go of the component Link Resolution. Executing a manipulation can lead to path traversal. The identification of this vulnerability is CVE-2026-79534. The attack may be launched remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as critical was found in mark3labs Mcp-filesystem-server 0.11.1. This vulnerability affects the function validatePath of the file filesystemserver/handler/helper.go of the component Link Resolution. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

mark3labs mcp-filesystem-server v0.11.1 is vulnerable to Directory Traversal due to an improper link resolution in validatePath (filesystemserver/handler/helper.go). When filepath.EvalSymlinks returns os.IsNotExist for a dangling symlink, the fallback validates only the parent directory and returns the unresolved path, so write_file (and modify_file, copy_file, move_file, create_directory) follows a pre-existing dangling symlink located inside an allowed directory and creates a file outside the configured allowed directories.

The advisory is shared for download at traceforce.ai. This vulnerability was named CVE-2026-79534 since 08/25/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/29/2026). The MITRE ATT&CK project declares the attack technique as T1006.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Artificial Intelligence Software

Vendor

• mark3labs

Name

• Mcp-filesystem-server

Version

• 0.11.1

CPE 2.3info

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CPE 2.2info

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