Arbitrary file access via path-prefix allowlist bypass
Published Apr 29, 2026 · Updated Apr 29, 2026
Path traversal in geekgod382 filesystem-mcp-server 1.0.0 allows remote attackers to read or modify files outside configured roots. The server.py is_path_allowed function normalizes a supplied path with os.path.abspath, then authorizes any string sharing an allowed root's prefix instead of verifying directory ancestry. An attacker able to invoke an exposed file-management MCP tool can use a sibling-prefix path to read, create, overwrite, or delete files with the server process's permissions.
Summary
What happened
Path traversal in geekgod382 filesystem-mcp-server 1.0.0 allows remote attackers to read or modify files outside configured roots. The server.py is_path_allowed function normalizes a supplied path with os.path.abspath, then authorizes any string sharing an allowed root's prefix instead of verifying directory ancestry. An attacker able to invoke an exposed file-management MCP tool can use a sibling-prefix path to read, create, overwrite, or delete files with the server process's permissions.
The record
- CVE
- CVE-2026-7400
- Published
- Apr 29, 2026
- Updated
- Apr 29, 2026
- Vendor
- geekgod382
- Product
- filesystem-mcp-server
- Classifications
- CWE-22, T1485, T1005
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 29, 2026CVE publishedPublication date reported by the CVE source.
- Apr 29, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.0.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- ALLOWED_PATHS sibling-prefix bypass proof of conceptproof of concept · unverified
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Technologies
Your stack
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Your stack
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