Io Modelcontextprotocol Sdk
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Unbounded HTTP request-body buffering in the Model Context Protocol (MCP) Java SDK lets an unauthenticated remote client exhaust the JVM heap and render an MCP server unavailable. The flaw affects the Servlet-based SSE, Streamable HTTP, and Stateless server transports in io.modelcontextprotocol.sdk:mcp 0.8.0-0.12.0, mcp-core 0.13.0-0.18.3, 1.0.0-1.1.3, and 2.0.0-M1-2.0.0; a client simply streams an arbitrarily large POST body (including via chunked transfer encoding) until OutOfMemory conditions make the process unresponsive. Rated CVSS 3.1 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and affecting availability only, the impact is materially reduced for deployments that require authentication, enforce Origin/Host validation, or sit behind a reverse proxy, load balancer, or API gateway with a maximum-body-size limit, all of which reject the oversized request before the vulnerable read; no public exploit code and no confirmed active exploitation were identified at time of analysis.
Unbounded HTTP request-body buffering in the Model Context Protocol (MCP) Java SDK lets an unauthenticated remote client exhaust the JVM heap and render an MCP server unavailable. The flaw affects the Servlet-based SSE, Streamable HTTP, and Stateless server transports in io.modelcontextprotocol.sdk:mcp 0.8.0-0.12.0, mcp-core 0.13.0-0.18.3, 1.0.0-1.1.3, and 2.0.0-M1-2.0.0; a client simply streams an arbitrarily large POST body (including via chunked transfer encoding) until OutOfMemory conditions make the process unresponsive. Rated CVSS 3.1 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and affecting availability only, the impact is materially reduced for deployments that require authentication, enforce Origin/Host validation, or sit behind a reverse proxy, load balancer, or API gateway with a maximum-body-size limit, all of which reject the oversized request before the vulnerable read; no public exploit code and no confirmed active exploitation were identified at time of analysis.