CVE-2026-79534 Path traversal in n/a
An attacker can write or read files outside allowed directories by exploiting dangling symlinks in the MCP filesystem server.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-79534?
CVE-2026-79534 is a medium-severity path traversal vulnerability in n/a, published on 29 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-79534?
How do I fix CVE-2026-79534?
No fix has been published for CVE-2026-79534 yet. Limit exposure of the affected software until one is available.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-79534 being exploited?
There is no known exploitation of CVE-2026-79534 in the wild and no public exploit code.
Sources
Also known as GHSA-9c87-p3cg-99hj.