FastMCP has a Command Injection vulnerability - Gemini CLI

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Summary

CVECVE-2025-64340
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-03 16:16:23 UTC
Updated2026-04-21 01:09:14 UTC
DescriptionFastMCP 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.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS: 0.000240000 probability, percentile 0.065820000 (date 2026-04-22)

Problem Types: CWE-78 | CWE-78 CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
3.1[email protected]Secondary6.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
3.1CNADECLARED6.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Jlowin Fastmcp All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Jlowin Fastmcp affected < 3.2.0 Not specified

References

ReferenceSourceLinkTags
github.com/PrefectHQ/fastmcp/pull/3522 [email protected] github.com Issue Tracking, Patch
github.com/PrefectHQ/fastmcp/security/advisories/GHSA-m8x7-r2rg-vh5g 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com Exploit, Patch, Vendor Advisory
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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