Transport security (MCP)
MCP transport security refers to the protections the Model Context Protocol specification requires for exchanging messages, which differ by transport. For stdio, where a client spawns the server as a local subprocess, the specification treats the operating system's process boundary as the trust mechanism and expects credentials from the environment rather than a network auth flow. For Streamable HTTP, the specification's security guidance is explicit: a server MUST validate the Origin header on incoming connections to prevent DNS rebinding attacks, SHOULD bind only to localhost rather than all interfaces when running locally, and SHOULD implement authentication -- without which an attacker's web page could use DNS rebinding to reach a server a user only intended to run locally. Treating every transport as equally exposed, or skipping these checks because a server 'just runs locally,' is a common and avoidable gap.
By AdminKit team, Netbase JSC · Updated