CVE-2025-64340
Published:April 03, 2026
Updated:April 26, 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.
Affected Packages
https://github.com/PrefectHQ/fastmcp.git (GITHUB):
Affected version(s) >=v0.1.0 <v3.2.0Fix Suggestion:
Update to version v3.2.0fastmcp (PYTHON):
Affected version(s) >=0.1.0 <3.2.0Fix Suggestion:
Update to version 3.2.0Related ResourcesĀ (5)
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Contact UsCVSS v4
Base Score:
5.4
Attack Vector
LOCAL
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
PASSIVE
Vulnerable System Confidentiality
HIGH
Vulnerable System Integrity
HIGH
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
6.7
Attack Vector
LOCAL
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Weakness Type (CWE)
Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
EPSS
Base Score:
0.02