CVE-2026-18482

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Command Injection in Neo.mjs MCP FileSystemService

Publication date: 2026-08-20

Last updated on: 2026-09-03

Assigner: CERT/CC

Description

Neo.mjs contains a command injection vulnerability within the FileSystemService.mjs component of the ai/mcp/server/file-system MCP server, where the checkSyntax() and runPlaywrightTest() functions unsafely interpolate caller-controlled absolutePath values into shell commands, enabling arbitrary OS command execution when an AI agent is induced to invoke these tools. Commit 88c77fc fixes these vulnerabilities.

CVSS Scores

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Meta Information

Published

2026-08-20

Last Modified

2026-09-03

Generated

2026-09-09

AI Q&A

2026-08-20

EPSS Evaluated

2026-09-07

NVD

CVE-2026-18482

EUVD

EUVD-2026-63326

Affected Vendors & Products

Vendor	Product	Version / Range
neomjs	neo	to 88c77fc (inc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-78	The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.

Attack-Flow Graph

Executive Summary

Neo.mjs has a command injection flaw in the FileSystemService.mjs component. The checkSyntax() and runPlaywrightTest() functions improperly insert user-controlled file paths into shell commands, allowing attackers to execute arbitrary operating system commands if they trick an AI agent into using these tools.

Detection Guidance

To detect this vulnerability, inspect the Neo.mjs file-system MCP server for unsafe shell command execution. Check if the FileSystemService.mjs component uses exec() with user-supplied paths. Commands like grep -r 'exec(' FileSystemService.mjs or checking for metacharacters in paths may help identify vulnerable code.

Impact Analysis

An attacker could gain control of the system hosting the Neo.mjs server by exploiting this flaw. This could lead to data theft, system damage, or further network compromise if the server has access to sensitive resources.

Compliance Impact

This vulnerability could lead to unauthorized access to personal or health data, violating GDPR and HIPAA requirements for data protection and access controls. Organizations using affected versions may face compliance violations and penalties.

Mitigation Strategies

Update Neo.mjs to commit 88c77fc or later, which replaces exec() with execFile() to prevent shell command injection. Ensure path containment checks use fs.realpath and path.relative to handle symlinks safely. Avoid relying on path-based sandboxing for execution tools.

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