CVE-2025-66401 is an OS command injection vulnerability identified in the kapilduraphe mcp-watch security scanner for Model Context Protocol (MCP) servers, affecting versions 0.1.2 and earlier. The vulnerability resides in the MCPScanner class's cloneRepo method, which accepts a user-supplied githubUrl parameter. This parameter is passed directly to a system shell through the Node.js execSync function without any sanitization or validation. Because execSync executes shell commands synchronously, an attacker can append shell metacharacters and arbitrary commands to the githubUrl argument, resulting in arbitrary command execution on the host machine. This flaw violates CWE-78, indicating improper neutralization of special elements used in OS commands. The vulnerability requires no authentication or user interaction, making it remotely exploitable over the network. The impact includes full compromise of the host system, allowing attackers to read, modify, or delete data, install malware, or pivot to other network resources. The CVSS v3.1 base score is 9.8, reflecting critical severity with network attack vector, low attack complexity, no privileges required, and no user interaction needed. No patches or fixes have been published yet, and no known exploits are reported in the wild as of the publication date. However, the vulnerability's nature and ease of exploitation make it a high-risk threat for any environment using the affected versions of mcp-watch. Organizations relying on this tool for MCP server security scanning should consider immediate mitigation steps to prevent exploitation.

For European organizations, the impact of CVE-2025-66401 is substantial. Since mcp-watch is used to scan Model Context Protocol servers, which may be integral to critical infrastructure or enterprise environments, exploitation could lead to complete system compromise. Attackers could gain unauthorized access to sensitive data, disrupt operations by deleting or altering files, or deploy ransomware or other malware. The vulnerability's remote exploitability without authentication increases the risk of widespread attacks, potentially affecting multiple organizations simultaneously. The loss of confidentiality, integrity, and availability could have severe consequences, including regulatory penalties under GDPR if personal data is compromised. Additionally, organizations in sectors such as finance, energy, telecommunications, and government are particularly vulnerable due to their reliance on MCP servers and the critical nature of their operations. The absence of known exploits currently provides a window for proactive defense, but the critical severity score demands urgent attention to avoid potential future attacks.

1. Immediate upgrade: Organizations should upgrade mcp-watch to a version beyond 0.1.2 once a patched release is available. 2. Input validation and sanitization: Until a patch is released, implement strict validation on the githubUrl input to reject any shell metacharacters or unexpected input patterns. 3. Execution environment hardening: Run mcp-watch with the least privileges possible, ideally within a sandboxed or containerized environment to limit the impact of any successful exploitation. 4. Disable or restrict execSync usage: If feasible, modify the source code to avoid using execSync with unsanitized inputs or replace it with safer alternatives that do not invoke a shell. 5. Network controls: Restrict network access to the mcp-watch service to trusted IPs and monitor network traffic for anomalous command execution attempts. 6. Monitoring and detection: Deploy host-based intrusion detection systems (HIDS) and log monitoring to detect suspicious command executions or unexpected process spawning. 7. Incident response readiness: Prepare incident response plans specific to command injection attacks, including forensic analysis and containment procedures. 8. Vendor engagement: Engage with the vendor kapilduraphe for updates, patches, and guidance on secure configurations.