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cve.new
GHSA-f897-62hf-6gxqhigh7.5

MCP TypeScript SDK: HTTP server transports and handlers did not limit request body size or JSON-RPC batch length

No CVE assignedCheck your stack

Impact

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.

Source excerpt · OSV

What to do

Upgrade every one you have installed.

OSV guidance

Affected packages

Start with the recorded fix for your release branch. Check your installed version and test compatibility before upgrading. Fixing this advisory does not rule out other vulnerabilities in the release.

Original source description

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.

References