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TI-2025-39774 Aliases CVE-2025-64340GHSA-m8x7-r2rg-vh5g

FastMCP has a Command Injection vulnerability - Gemini CLI

Priority HIGH 69CWE-78Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and GitHub. Impact type from CWE-78.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00748 55th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed fastmcp (jlowin): 3.2.0fastmcp (PyPI): 3.2.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
jlowinfastmcpbefore 3.2.03.2.0Patch availableCNA
—fastmcp (PyPI)before 3.2.03.2.0Patch availableGHSA-m8x7-r2rg-vh5g
  • fastmcp Vendorjlowin Affected before 3.2.0 Fixed in 3.2.0 Patch available CNA
  • fastmcp (PyPI) Vendor— Affected before 3.2.0 Fixed in 3.2.0 Patch available GHSA-m8x7-r2rg-vh5g

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:jlowin:fastmcp:*:*:*:*:*:*:*:*before 3.2.0Vulnerablejlowin
  • cpe:2.3:a:jlowin:fastmcp:*:*:*:*:*:*:*:* Versions before 3.2.0 Vulnerable ·jlowin

Remediation

  • Fix · CNA fastmcp (jlowin) Fixed in 3.2.0
  • Fix · GHSA-m8x7-r2rg-vh5g fastmcp (PyPI) Fixed in 3.2.0 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-64340
  2. 2026-10-03 Alias added: GHSA-m8x7-r2rg-vh5g

References

Exploit 1

Patch 1

Advisory 1

Other 2

  • TI-2026-25332 FastMCP OpenAPI Provider has an SSRF & Path Traversal Vulnerability CVSS 4.0CRITICAL 10.0
  • TI-2026-21575 FastMCP: Missing Consent Verification in OAuth Proxy Callback Facilitates Confused Deputy Vulnerabilities CVSS 4.0HIGH 8.2
  • TI-2025-42650 FastMCP OAuth Proxy token reuse across MCP servers CVSS 4.0HIGH 7.4
  • TI-2025-38984 FastMCP vulnerable to windows command injection in FastMCP Cursor installer via server_name CVSS 4.0MEDIUM 5.4
  • TI-2025-38983 FastMCP vulnerable to reflected XSS in client's callback page CVSS 4.0MEDIUM 5.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences