EleazarTorres0520/mcp-server-python-mpdjf3f3
highCreated from render-examples/mcp-server-python template
This MCP server is a template for deploying a Model Context Protocol server on Render. It provides a minimal example with a single 'hello' tool that g...
25@mcp.tool()
26def hello(name: str) -> str:
27 """Say hello to someone."""
28 return f"Hello, {name}!"// Exploitable only if MCP is exposed to untrusted prompts (network_exposed).
The 'hello' tool accepts a 'name' parameter of type str with no validation or sanitization. While the tool's purpose is to greet a user, the name is directly interpolated into the response string. If the MCP server is exposed to untrusted prompts (network_exposed), an attacker could inject content that might be interpreted by downstream systems or cause log injection. However, the primary risk is limited because the output is a simple string returned to the caller, not executed or stored unsafely.
ImpactAn attacker could inject special characters or long strings, potentially causing log injection or minor misbehavior in clients that process the response. No code execution or data breach is possible.
FixAdd input validation to ensure the name parameter is a reasonable length and contains only expected characters (e.g., alphanumeric and spaces). Consider sanitizing or escaping the output if it will be used in contexts where injection is a concern.
68if MCP_API_TOKEN:
69 app.add_middleware(BearerAuthMiddleware)// Network-exposed MCP; if deployed without token, all tools are unauthenticated.
The authentication middleware is only added if MCP_API_TOKEN is set. If the token is not configured (e.g., in local development), the server runs without any authentication, exposing all tools to unauthenticated access. The code prints a warning (line 77-80) but does not enforce authentication.
ImpactAn attacker can call the 'hello' tool without any token, potentially leading to abuse or information gathering. Since the tool is benign, the impact is limited, but it violates the intended security model.
FixConsider requiring authentication by default, or at least fail closed if no token is configured. Alternatively, document that the server must not be exposed to untrusted networks without a token.
31@mcp.custom_route("/health", methods=["GET"])
32async def health(request: Request) -> Response:
33 return JSONResponse({"status": "ok"})// Network-exposed MCP; health endpoint is intentionally public.
The /health endpoint is explicitly excluded from authentication in the BearerAuthMiddleware (line 43). While this is intentional for health checks, it exposes a public endpoint that could be used to probe the server's existence and potentially gather information about the server's status. The risk is low as it only returns a static JSON response.
ImpactAn unauthenticated attacker can verify the server is running and reachable. No sensitive data is leaked.
FixIf health checks require authentication, remove the bypass. Otherwise, ensure no sensitive information is returned from the health endpoint.