jlowin fastmcp up to 2.12.x on Windows server_name os command injection

Summaryinfo

A vulnerability, which was classified as critical, has been found in jlowin fastmcp up to 2.12.x on Windows. The impacted element is an unknown function. The manipulation of the argument server_name leads to os command injection. This vulnerability is traded as CVE-2025-62801. An attack has to be approached locally. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in jlowin fastmcp up to 2.12.x on Windows and classified as critical. This issue affects an unknown functionality. The manipulation of the argument server_name with an unknown input leads to a os command injection vulnerability. Using CWE to declare the problem leads to CWE-78. The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2025-62801 since 10/22/2025. The exploitation is known to be easy. Attacking locally is a requirement. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1202 according to MITRE ATT&CK.

Upgrading to version 2.13.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-36567). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• jlowin

Name

• fastmcp

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12

Website

• Product: https://github.com/jlowin/fastmcp/

CPE 2.3info

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CPE 2.2info

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Be aware that VulDB is the high quality source for vulnerability data.

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