CVE-2025-64340 PUBLISHED

FastMCP has a Command Injection vulnerability - Gemini CLI

Assigner: GitHub_M
Reserved: 30.10.2025 Published: 03.04.2026 Updated: 03.04.2026

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.

Metrics

CVSS Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
CVSS Score: 6.7

Product Status

Vendor jlowin
Product fastmcp
Versions
  • Version < 3.2.0 is affected

References

Problem Types

  • CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') CWE