CVE-2026-52869 MCP Python SDK: HTTP transports serve session requests without verifying the authenticated principal

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol MCP. Prior to 1.27.2, the SSE and stateful Streamable HTTP transports mcp.server.sse.SseServerTransport and mcp.server.streamablehttpmanager.StreamableHTTPSessionManager route requests to existing...

PT-2026-60036

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...

GHSA-VRXG-GM77-7Q5G 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...