The NSA published its first design guidance for MCP.

The NSA released authoritative MCP security guidance this month, walking through the protocol's inverted client-server pattern, unverified task propagation between chained servers, and arbitrary-code-execution exposure (Adversa AI). When the NSA ships design guidance for your protocol, it's no longer a hobbyist plumbing layer, it's critical agent infrastructure with a government baseline you can audit against. Pair it with the finding that ~40% of remote MCP servers expose tools with no auth, and Censys counting 12,520 internet-reachable MCP services (PipeLab). Treat MCP endpoints like any other API surface. Internet-facing means attacker-facing.