CVE-2025-67366

HighPublic PoC

Published: 07 January 2026

Published

07 January 2026

Modified

29 January 2026

KEV Added

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Patch

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CVSS Score 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Score 0.0008 23.8th percentile

Risk Priority 15 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-67366 is a high-severity Relative Path Traversal (CWE-23) vulnerability in Sylphx Filesystem-Mcp. Its CVSS base score is 7.5 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 23.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

This vulnerability is AI-related — categorised as AI Agent Protocols and Integrations; in the Protocol-Specific Risks risk domain.

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique.

Threat & Defense Details

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1005 Data from Local System Collection

Adversaries may search local system sources, such as file systems, configuration files, local databases, virtual machine files, or process memory, to find files of interest and sensitive data prior to Exfiltration.

attack.mitre.org →

Why these techniques?

Remote unauthenticated path traversal in public-facing MCP file server directly enables T1190 exploitation and unauthorized local file reads (T1005).

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

@sylphxltd/filesystem-mcp v0.5.8 is an MCP server that provides file content reading functionality. Version 0.5.8 of filesystem-mcp contains a critical path traversal vulnerability in its "read_content" tool. This vulnerability arises from improper symlink handling in the path validation mechanism: the resolvePath…

function checks path validity before resolving symlinks, while fs.readFile resolves symlinks automatically during file access. This allows attackers to bypass directory restrictions by leveraging symlinks within the allowed directory that point to external files, enabling unauthorized access to files outside the intended operational scope.

Deeper analysisAI

CVE-2025-67366 is a critical path traversal vulnerability (CWE-23) affecting version 0.5.8 of @sylphxltd/filesystem-mcp, an MCP server that provides file content reading functionality. The flaw exists in the "read_content" tool due to improper symlink handling in the path validation mechanism. Specifically, the resolvePath function performs path validity checks before resolving symlinks, while the underlying fs.readFile operation automatically resolves symlinks during file access. This discrepancy allows attackers to bypass directory restrictions. The vulnerability has a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N).

Remote attackers require no privileges or user interaction to exploit this vulnerability over the network with low complexity. By placing symlinks within the allowed directory that point to files outside the intended operational scope, attackers can trick the read_content tool into accessing and disclosing unauthorized file contents. Successful exploitation results in high-impact confidentiality violations, enabling the reading of sensitive data beyond the server's restricted filesystem boundaries.

Further details, including potential patches or mitigation guidance, are documented in the project's GitHub repository at https://github.com/sylphxltd/filesystem-mcp and the associated issue tracker at https://github.com/sylphxltd/filesystem-mcp/issues/134. Security practitioners should review these resources for updates on remediation steps.