The Model Context Protocol (MCP) is a lightweight, open protocol functioning as JSON-RPC over HTTP, facilitating standardized discovery and invocation of tools. MCP defines three roles: MCP Hosts (applications accessing capabilities), MCP Clients (initiators of requests), and MCP Servers (services exposing functionalities). Windows 11 will incorporate MCP to enable developers to create intelligent applications leveraging generative AI. An early preview of MCP capabilities will be available for developer feedback.
MCP introduces security risks, including cross-prompt injection, authentication gaps, credential leakage, tool poisoning, lack of containment, limited security review, registry risks, and command injection. To address these, Windows 11's MCP Security Architecture will establish security requirements for MCP servers, ensuring user safety and transparency, enforcing least privilege, and implementing security controls like proxy-mediated communication, tool-level authorization, a central server registry, and runtime isolation.
MCP servers must comply with security requirements, including mandatory code signing, unchanged tool definitions at runtime, security testing, mandatory package identity, and declared privileges. An early private preview of MCP server capability will be offered to developers post-Microsoft Build for feedback, with a secure-by-default enforcement strategy planned for broader availability. Microsoft aims to enhance defenses continuously and collaborate with partners to bolster MCP's security framework.