CVE-2025-62801 is an OS command injection vulnerability identified in the FastMCP framework developed by jlowin, affecting versions prior to 2.13.0. FastMCP is a standard framework used to build MCP (Multi-Channel Processing) applications, commonly deployed on Windows hosts. The vulnerability stems from improper neutralization of special elements in the server_name input field, which is used in OS command construction. An attacker who can influence this field can inject arbitrary commands that the Windows OS will execute with the privileges of the FastMCP process. The CVE is classified under CWE-78, indicating a failure to sanitize inputs before incorporating them into OS commands. Exploitation requires the attacker to have low privileges (PR:L), perform some user interaction (UI:A), and have local access (AV:L). The vulnerability impacts confidentiality, integrity, and availability with high impact metrics (VC:H, VI:H, VA:H) because arbitrary command execution can lead to data theft, system manipulation, or denial of service. The vulnerability has a CVSS 4.0 base score of 5.4, reflecting medium severity. No known exploits have been reported in the wild, but the risk remains significant due to the potential for privilege escalation and lateral movement within affected environments. The issue is resolved in FastMCP version 2.13.0, which properly sanitizes the server_name field to prevent command injection.

For European organizations, this vulnerability poses a moderate risk primarily to Windows-based systems running FastMCP versions prior to 2.13.0. Successful exploitation could allow attackers to execute arbitrary OS commands, potentially leading to unauthorized data access, system compromise, or disruption of MCP applications critical for business operations. Organizations in sectors relying heavily on MCP applications—such as telecommunications, finance, and manufacturing—may face operational disruptions or data breaches. The requirement for local access and user interaction reduces the likelihood of remote exploitation but does not eliminate insider threats or attacks leveraging social engineering. Additionally, compromised systems could serve as footholds for further lateral movement within networks, increasing the overall risk posture. The absence of known exploits in the wild suggests limited current active exploitation but does not preclude future attacks, especially as threat actors develop proof-of-concept exploits. Therefore, European entities should consider this vulnerability a significant operational security concern until patched.

1. Upgrade all FastMCP installations to version 2.13.0 or later immediately to apply the official fix that neutralizes the command injection vector. 2. Restrict access to the server_name field input to trusted users and processes only, implementing strict input validation and sanitization at the application layer as an additional safeguard. 3. Employ application whitelisting and endpoint detection and response (EDR) tools to monitor and block suspicious command execution activities on Windows hosts running FastMCP. 4. Conduct regular audits of user privileges and minimize permissions for accounts interacting with FastMCP to reduce the risk of privilege escalation. 5. Implement network segmentation to isolate critical MCP application servers from less secure network zones, limiting potential lateral movement. 6. Educate users and administrators about the risks of social engineering and the importance of cautious interaction with MCP application inputs. 7. Monitor logs for unusual command execution patterns or anomalies related to the server_name field to detect potential exploitation attempts early.