CVE-2026-48989

CVE-2026-48989 affects Windows-MCP HTTP transports that expose an unauthenticated control plane with wildcard CORS, enabling arbitrary PowerShell execution via the PowerShell tool when accessed from arbitrary origins. Root cause: FastMCP instance built without authentication and middleware applyi...

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...