GHSA-f897-62hf-6gxq

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

This page contains facts from public vulnerability sources. Check the original advisory before updating.

### Summary In affected versions, MCP servers reachable over HTTP put no limit on the size of a POST body or on the number of messages in a JSON-RPC batch. Large requests could exhaust the server's memory, and one long batch could block it from serving anyone else. No credentials were needed, unless your application authenticates requests before they reach the SDK. ### Am I affected? Yes, if clients you do not fully trust can reach your server over Streamable HTTP. A body parser such as `express.json()` does not protect you, because it does not limit batch length. Servers that only use stdio are not affected. Affected versions: - `@modelcontextprotocol/sdk` 1.10.0 through 1.30.0 - `@modelcontextprotocol/server` 2.0.0 - `@modelcontextprotocol/node` 2.0.0 - `@modelcontextprotocol/hono` 2.0.0 ### Fix Upgrade to: - 1.x: `@modelcontextprotocol/sdk` 1.30.1 or later - 2.x: `@modelcontextprotocol/server` 2.1.0, `@modelcontextprotocol/node` 2.1.0 and `@modelcontextprotocol/hono` 2.0.1 or later. Upgrade every one you have installed. Bodies over 4 MiB now get `413`, and batches over 100 messages get `400`. If your clients send larger bodies, raise the new `maxRequestBodySize` option. If you cannot upgrade yet, cap request body size in a reverse proxy.

CVSS 7.5 · High · Fix available

Published

2026-10-27T19:02:00Z

Updated

2026-10-27T19:15:22.388698300Z

Stack: node

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