Security Notes (Quickstart Resources)

These examples are intentionally minimal and optimized for learning. Before using similar patterns in production, apply basic hardening.

If You Expose An MCP Server Over A Network (HTTP/SSE/WebSocket)

• Require authentication: do not expose unauthenticated tool endpoints to the public internet.
• Treat browsers as hostile:
  • Do not use wildcard CORS (Access-Control-Allow-Origin: *) on authenticated endpoints.
  • Do not reflect Origin without allowlist validation.
  • Prefer an explicit origin allowlist.
• Bound resource usage:
  • Set an explicit maximum request body size.
  • Add timeouts to outbound requests.
  • Add rate limits (per user/token and/or per IP).
• Avoid RCE primitives in tools:
  • Avoid eval / dynamic code execution.
  • Avoid invoking a shell with attacker-controlled input (exec, sh -c, shell=True).
  • If you must run commands, enforce strict allowlists and pass arguments as arrays (no shell).
• Don't leak secrets: redact Authorization, cookies, and API keys from logs.

Local-Only Usage

If you run these examples locally via stdio transports, your main risks are still:

• accidentally adding dangerous tools (filesystem/shell) without strict controls
• leaking secrets via logs or environment

When in doubt: keep tool capability narrow and add input validation.