CVE-2025-64340 MEDIUM

CVE-2025-64340: FastMCP has a Command Injection vulnerability - Gemini CLI

Vendor Jlowin
Product fastmcp
Weakness CWE-78
Published April 3, 2026
Last update April 3, 2026

CVSS base score

6.7/10
Attack vector Local
Attack complexity High
Privileges required Low
User interaction Required
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H

What the vulnerability does

01Description

FastMCP is the standard framework for building MCP applications. Prior to version 3.2.0, server names containing shell metacharacters (e.g., &) can cause command injection on Windows when passed to fastmcp install claude-code or fastmcp install gemini-cli. These install paths use subprocess.run() with a list argument, but on Windows the target CLIs often resolve to .cmd wrappers that are executed through cmd.exe, which interprets metacharacters in the flattened command string. This issue has been patched in version 3.2.0.

Key dates

02Disclosure timeline

April 3, 2026 CVE published
April 3, 2026 Record updated