# CVE-2026-79534: mark3labs mcp-filesystem-server directory traversal in validatePath

Source: https://junglewise.ai/threats/cve-2026-79534-mark3labs-mcp-filesystem-server-v0-11-1-is-vulnerable-to  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-29. Updated: 2026-09-29  
License: CC BY 4.0 with a link back

CVE-2026-79534 · Severity: info · Published 2026-09-29

mcp-filesystem-server is a file access service used by AI agents to read and write files on systems. A vulnerability in symlink handling allows an attacker to create files outside the configured allowed directories by placing a dangling symlink inside an allowed directory. An attacker must first plant the symlink, but exploitation does not require authentication or special privileges.

Vendors: [Mark3labs](https://junglewise.ai/threats/vendors/mark3labs).

## Quick answers

**Is CVE-2026-79534 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-79534 being exploited in the wild.

**How severe is CVE-2026-79534?** Informational severity, published 29 September 2026.

**Which products and versions are affected?** Mark3labs Mcp-Filesystem-Server v0.11.1 and main commit ba3f07f.

**Is there a fix for CVE-2026-79534?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-79534 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-79534?** Check whether you run Mark3labs Mcp-Filesystem-Server at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The validatePath function in helper.go improperly handles dangling symlinks: when filepath.EvalSymlinks fails with os.IsNotExist, the code validates only the parent directory and returns the unresolved path instead of re-checking the final destination. This allows write_file, modify_file, copy_file, move_file, and create_directory operations to follow the planted symlink and write outside the allow-list. The vulnerability requires the attacker to pre-plant the symlink within an allowed directory.

## Affected products

- mark3labs mcp-filesystem-server v0.11.1 and main commit ba3f07f

## Timeline

- 2026-08-21: disclosed: Reported to maintainer by Traceforce
- 2026-09-10: advisory: CVE ID assigned by MITRE
- 2026-09-29: other: NVD publication

## References

- [https://www.traceforce.ai/security-advisories/cve-2026-79534](https://www.traceforce.ai/security-advisories/cve-2026-79534)