Medium severity6.7NVD Advisory· Published Apr 3, 2026· Updated Apr 21, 2026
CVE-2025-64340
CVE-2025-64340
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.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
fastmcpPyPI | < 3.2.0 | 3.2.0 |
Affected products
1Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
5- github.com/PrefectHQ/fastmcp/pull/3522nvdIssue TrackingPatchWEB
- github.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5gnvdExploitPatchVendor AdvisoryWEB
- github.com/advisories/GHSA-m8x7-r2rg-vh5gghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2025-64340ghsaADVISORY
- github.com/jlowin/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5gghsaWEB
News mentions
1- Open-source MCP server monitoring for Python appsHelp Net Security · May 7, 2026