CVE-2025-64340CWE-78

FastMCP has a Command Injection vulnerability - Gemini CLI

Medium · published April 3, 2026

CVSS v3.1
6.7
EPSS
1%
Percentile
53.9
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
6.7 · MEDIUM
Vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.00735 · 53.9th percentile
Weakness
CWE-78 · Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Published
2026-04-03T15:16Z
EPSS history
Timeline
  • 03 APR 15:16Z
    FastMCP has a Command Injection vulnerability - Gemini CLI
    cvelistv5