gmaps-mcp's unauthenticated HTTP transport allows unlimited Google Maps API calls at operator expense
Date: 2026-05
Affected: pip/gmaps-mcp
Attack vector: auth-bypass
Category: vulnerability-disclosure
Severity: High
CWE: CWE-20
CWE-306

## Unauthenticated HTTP Transport Allows Unlimited Google Maps API Calls at Operator Expense The `gmaps-mcp` codebase was reviewed at commit `e671db68c804c9e67d51582d3280839ffa65f127` and three issues worth flagging were discovered — one high-severity, one medium, one structural. There were no preexisiting CVEs for this package yet and the repository had no prior security issues. The primary issue is that the HTTP transport in `server.py` skips authentication entirely when `MCP_API_KEY` is not set — which is the default, since `.env.example` ships the key as a blank value. Any unauthenticated caller who knows the server's public URL can invoke all six tools and generate live, billed Google Maps API requests against the operator's key. Because the README explicitly instructs operators to expose the server via ngrok (`ngrok http 8000`, then point MCP clients at the ngrok URL), this configuration gets deployed internet-facing as a matter of normal usage. **Affected files and exact lines:** `src/google_maps_mcp/server.py`, lines 186–192: ```python expected_key = os.getenv("MCP_API_KEY") if not expected_key: # If no MCP_API_KEY is set, allow all requests (development mode) return await call_next(request) if api_key != expected_key: return JSONResponse( {"error": "Invalid or missing API key. Provide X-API-Key header."}, status_code=401 ) ``` `run.py` lines 37 and 38 bind to `0.0.0.0:8000` by default (`MCP_HOST=0.0.0.0`, `MCP_PORT=8000`). No ra


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