fast-filesystem-mcp has a Path Traversal vulnerability
fast-filesystem-mcp version 3.4.0 contains a critical path traversal vulnerability in its file operation tools including fast_read_file. This vulnerability arises from improper path validation that fails to resolve symbolic links to their actual physical paths. The safePath and isPathAllowed functions use path.resolve() which does not handle symlinks, allowing attackers to bypass directory access restrictions by creating symlinks within allowed directories that point to restricted system paths. When these symlinks are accessed through valid path references, the validation checks are circumvented, enabling access to unauthorized files.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | fast-filesystem-mcp | <= 3.4.0 | no fix |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N- Weakness (CWE)
CWE-24- Platform
- npm
- Package
fast-filesystem-mcp- Disclosed
- 07.01.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-j893-m93w-jwjw - CC BY 4.0
Vulnerability history: fast-filesystem-mcp
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 01.2026 04.2026
- Without a fix
- 2
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Low 1
Disclosures per year
- 2026: 2
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fast-filesystem-mcp has a Path Traversal vulnerability this entry
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