Arbitrary file read via unconstrained path resolution
Published Aug 27, 2026 · Updated Aug 27, 2026
Path traversal in mcp-file-context-server 1.0.0 allows remote attackers to read files outside the working directory via read_context. The handler resolves a caller-controlled path against process.cwd(), checks only access, and passes it to fs.stat and fs.readFile without enforcing containment. The attacker must be able to invoke the MCP tool, and returned data is limited to files readable by the server process.
Summary
What happened
Path traversal in mcp-file-context-server 1.0.0 allows remote attackers to read files outside the working directory via read_context. The handler resolves a caller-controlled path against process.cwd(), checks only access, and passes it to fs.stat and fs.readFile without enforcing containment. The attacker must be able to invoke the MCP tool, and returned data is limited to files readable by the server process.
The record
- CVE
- CVE-2026-81486
- Published
- Aug 27, 2026
- Updated
- Aug 27, 2026
- Vendor
- bsmi021
- Product
- mcp-file-context-server
- Classifications
- CWE-22, T1005
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 27, 2026CVE publishedPublication date reported by the CVE source.
- Aug 27, 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?
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- Affected versionversion=1.0.0
What conditions does exploitation require?
What is affected?
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
- GitHub issue read_context traversal reproduction requestproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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