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CVE-2025-64340

FastMCP has a Command Injection vulnerability - Gemini CLI

Published: Apr 3, 2026Updated: Apr 21, 2026 Sources: CVE List NVDCWE-78
NVD MITRE
6.7CVSSMEDIUM
EPSS Score
0.7%
Top 49.9%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available

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.

CVSS Vector Breakdown

AV:LAC:HPR:LUI:RS:UC:HI:HA:H
Exploitability
AV:LAttack Vector
Local
AC:HAttack Complexity
High
PR:LPrivileges Required
Low
UI:RUser Interaction
Required
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
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Weaknesses

CWE-78

Affected Products

fastmcpjlowin
Library
AI / ML / ai-agent-tooling
jlowinindividual-devAI / MLaka fastmcp

Attack Graph

Products CVE Techniques Tactics

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Exploitability

Official Patch Available

MITRE ATT&CK

1 technique
Execution
View detailed technique mapping

References

https://github.com/PrefectHQ/fastmcp/pull/3522
github.com
https://github.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g
github.com

Timeline

Published
Apr 3, 2026
Last Updated
Apr 21, 2026

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