CVE-2026-109527

Name of the Vulnerable Software and Affected Versions mcp versions prior to 1.29.1 mcp versions 2.0.0a1 through 2.0.1

Description The Streamable HTTP session manager, SSE message endpoint, and OAuth authorization-server routes buffer complete HTTP request bodies without enforcing a maximum size. An unauthenticated remote client can send a large declared or streamed request body that consumes multiple times the body size in process memory, potentially exhausting memory or terminating the server. Stdio-only servers and deployments with an effective upstream request-size limit are not affected. Applications using StreamableHTTPServerTransport directly are responsible for enforcing their own limits.

Recommendations Update to version 1.29.1. Update to version 2.1.0.