They host a repo with lots of what they call "reference" implementations, including this one for postgres which naively takes a query from a request and shoves it at your database with no validation, escaping, anything: https://github.com/modelcontextprotocol/servers/blob/7d6cdb6...
There's an issue calling this out, and it's been labeled a bug, but still.
When you go to their documentation, the only example of actually building a server is this section where they just...use an LLM to build it. Here's their prompt:
> Build an MCP server that: - Connects to my company's PostgreSQL database - Exposes table schemas as resources - Provides tools for running read-only SQL queries - Includes prompts for common data analysis tasks
So, I think there's a fairly high chance that all of the "reference implementations" they're hosting are AI generated with basically no security considerations or code reviews made.