MCP Python SDK: HTTP transports serve session requests without verifying the authenticated principal

SummaryIn affected versions, the SSE and Streamable HTTP server transports routed incoming requests to an existing session based only on the session identifier, without verifying that the request was authenticated as the same principal that created the session. Anyone who learned or guessed a...

Windows-MCP: HTTP transports expose unauthenticated PowerShell control with wildcard CORS

HTTP transports expose unauthenticated PowerShell control with wildcard CORSThere is an issue in the SSE and Streamable HTTP transport modes. The default stdio mode is not affected, but the documented HTTP modes expose the MCP control plane without authentication and add wildcard CORS handling...

PYSEC-2026-3425 Windows-MCP: HTTP transports expose unauthenticated PowerShell control with wildcard CORS

HTTP transports expose unauthenticated PowerShell control with wildcard CORS There is an issue in the SSE and Streamable HTTP transport modes. The default stdio mode is not affected, but the documented HTTP modes expose the MCP control plane without authentication and add wildcard CORS handling...

Windows-MCP: HTTP transports expose unauthenticated PowerShell control with wildcard CORS

HTTP transports expose unauthenticated PowerShell control with wildcard CORS There is an issue in the SSE and Streamable HTTP transport modes. The default stdio mode is not affected, but the documented HTTP modes expose the MCP control plane without authentication and add wildcard CORS handling...