CVE-2025-64340 Details
Description
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.
A command injection vulnerability has been identified in FastMCP versions prior to 3.2.0. The issue arises when server names containing shell metacharacters, such as '&', are passed to the 'fastmcp install claude-code' or 'fastmcp install gemini-cli' commands. On Windows, these commands are executed through 'cmd.exe', which interprets the metacharacters in the command string, leading to arbitrary command execution. This vulnerability does not affect macOS or Linux, and it has been patched in FastMCP version 3.2.0 by validating server names to reject shell metacharacters.
Users can update to FastMCP version 3.2.0 or later, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Apr 3, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g | CISA-ADP | ExploitPatchVendor Advisory |
| https://github.com/PrefectHQ/fastmcp/pull/3522 | [email protected] | Issue TrackingPatch |
| https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g | [email protected] | ExploitPatchVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-78 | Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| jlowin fastmcp | < 3.2.0 |
CPE
Remediation
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Change History
6 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 24, 2026 | CVE Translated | [email protected] |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 21, 2026 | Initial Analysis | [email protected] |
| Apr 3, 2026 | New CVE Received | [email protected] |
| Apr 3, 2026 | CVE Modified | CISA-ADP |