Please do not report security vulnerabilities through public GitHub issues.

Instead, email security@coplay.dev with:

• A clear description of the issue
• Steps to reproduce or a proof-of-concept
• The version of MCP for Unity affected (UPM package + Python server)
• Your OS, Unity Editor version, and MCP client
• Optional: a suggested fix

We aim to acknowledge reports within 3 business days and to share an initial assessment within 10 business days. Critical fixes are released as patch versions on both main and the beta channel.

MCP for Unity is intentionally fail-closed:

• HTTP Local binds to loopback only by default (127.0.0.1, localhost, ::1). LAN bind (0.0.0.0, ::) requires explicit opt-in via Allow LAN Bind (HTTP Local) in Advanced Settings.
• HTTP Remote requires https:// by default. Plaintext http:// for remote endpoints requires explicit opt-in via Allow Insecure Remote HTTP.
• Remote-hosted mode requires API key authentication. See Remote Server Auth.

If you find a way to bypass any of these guards, that qualifies as a security vulnerability and warrants a private report.

• Remote code execution via crafted MCP messages
• Auth bypass on remote-hosted server
• Filesystem read/write outside the intended Unity project root
• Network requests that escape the configured allow-list
• Credential or API-key leakage in logs, telemetry, or error responses

• Tool actions that intentionally modify the Unity project (that's the product)
• Issues that require an attacker to already have shell access to the host
• Vulnerabilities in third-party dependencies — please report those upstream first; we'll bump our pins after the upstream fix lands

Once a fix is shipped, we publish a security advisory on the GitHub Security tab and credit the reporter (unless they prefer anonymity).