GHSA-f897-62hf-6gxq: MCP TypeScript SDK: HTTP server transports and handlers did not limit request body size or JSON-RPC batch length

Summary

Affected versions of the MCP TypeScript SDK put no limit on the size of HTTP POST bodies or on the number of messages in a JSON-RPC batch, so large requests can exhaust server memory and a long batch can block other clients. Exploitation needs no credentials unless the application authenticates requests before they reach the SDK, and stdio-only servers are not affected.

Mitigation

Upgrade @modelcontextprotocol/sdk to 1.30.1 or later for 1.x, and to @modelcontextprotocol/server 2.1.0, @modelcontextprotocol/node 2.1.0 and @modelcontextprotocol/hono 2.0.1 or later for 2.x, upgrading every installed package. Bodies over 4 MiB now get 413 and batches over 100 messages get 400; raise the maxRequestBodySize option if clients send larger bodies. If upgrading is not possible yet, cap request body size in a reverse proxy.

Affected packages in the Exposure Registry

Matched by package name and ecosystem. Each entry shows whether the package delegates to a language model and how many tracked packages depend on it.

• @modelcontextprotocol/nodenpmNo LLM dependency detected · 2 tracked dependents
• @modelcontextprotocol/sdknpmLLM dependency since 2024-11-11 · 19 tracked dependents
• @modelcontextprotocol/servernpmNo LLM dependency detected · 3 tracked dependents

Topics

• Model Context Protocol

Related items

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• HighGHSA-46jr-4wx8-v453: MCP TypeScript SDK: One HTTP request within the default size limit could exhaust server memory during validationSame vendor · GitHub Advisory Database
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