CVE-2025-66401 is an OS command injection vulnerability identified in the kapilduraphe mcp-watch security scanner for Model Context Protocol (MCP) servers, specifically affecting versions 0.1.2 and earlier. The vulnerability resides in the MCPScanner class’s cloneRepo method, which accepts a githubUrl parameter from users and passes it directly to the system shell via Node.js’s execSync function without any sanitization or validation. This improper neutralization of special elements (CWE-78) allows attackers to append shell metacharacters and arbitrary commands to the URL, resulting in arbitrary command execution on the host machine. The flaw requires no authentication or user interaction, making it remotely exploitable over the network. The CVSS 3.1 base score is 9.8 (critical), reflecting the vulnerability’s high impact on confidentiality, integrity, and availability. Exploitation could lead to full system compromise, data theft, or disruption of MCP server operations. No patches or fixes are currently linked, and no exploits have been observed in the wild, but the vulnerability’s nature and severity warrant immediate attention. MCP servers are often used in specialized industrial or network contexts, and the mcp-watch tool is designed to scan these servers for security issues, meaning the vulnerability could be leveraged to undermine the security posture of critical infrastructure. The lack of input sanitization in a security tool ironically introduces a severe risk vector that attackers could exploit to gain persistent access or pivot within affected environments.

For European organizations, the impact of CVE-2025-66401 is substantial. MCP servers may be integral to industrial control systems, telecommunications, or specialized network environments, and the mcp-watch tool is used to audit these servers’ security. Exploitation could allow attackers to execute arbitrary commands remotely, leading to full system compromise, data exfiltration, disruption of services, or lateral movement within networks. This could affect confidentiality by exposing sensitive data, integrity by allowing unauthorized changes, and availability by causing service outages. Critical sectors such as energy, manufacturing, and telecommunications in Europe could face operational disruptions or safety risks. The vulnerability’s ease of exploitation and lack of authentication requirements increase the likelihood of attacks, especially in environments where mcp-watch is deployed without strict network segmentation or monitoring. Even though no known exploits are reported yet, the critical CVSS score and potential for severe damage necessitate proactive defense measures to protect European infrastructure and enterprises.

1. Immediately audit all deployments of mcp-watch and identify versions 0.1.2 or earlier in use. 2. Apply patches or updates from the vendor once available; if no patch exists, consider disabling or isolating the tool until a fix is released. 3. Implement strict input validation and sanitization on the githubUrl parameter to prevent shell metacharacter injection. 4. Replace execSync calls with safer alternatives that do not invoke the shell or use parameterized APIs. 5. Employ application sandboxing or containerization to limit the impact of potential command execution. 6. Restrict network access to mcp-watch instances using firewalls and network segmentation to reduce exposure. 7. Monitor system logs and process execution for unusual commands or patterns indicative of exploitation attempts. 8. Conduct security awareness training for administrators managing MCP servers and related tools. 9. Consider deploying host-based intrusion detection systems (HIDS) to detect anomalous behavior. 10. Review and harden overall MCP server security posture to reduce attack surface.