CVE-2025-62801: FastMCP vulnerable to windows command injection in FastMCP Cursor installer via server_name

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-10-28 · updated 2026-10-08
Weakness: CWE-78

Description

FastMCP is the standard framework for building MCP applications. Versions prior to 2.13.0, a command-injection vulnerability lets any attacker who can influence the server_name field of an MCP execute arbitrary OS commands on Windows hosts that run fastmcp install cursor. This vulnerability is fixed in 2.13.0.

Affected products

jlowin fastmcp: before 2.13.0 — fixed in 2.13.0

How to fix

Upgrade to a fixed version: jlowin fastmcp 2.13.0. Check the vendor advisory for mitigations.

References

https://github.com/jlowin/fastmcp/security/advisories/GHSA-rj5c-58rq-j5g5
https://github.com/jlowin/fastmcp/security/advisories/GHSA-rj5c-58rq-j5g5

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