Live › vulnerability › GHSA-f897-62hf-6gxq
Go to dashboardThe MCP TypeScript SDK's HTTP server transports and handlers did not cap POST body size or the number of messages in a JSON-RPC batch. A remote client can send oversized or very long batches, exhausting server memory and blocking other users.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-27 19:04 UTC. All times on this page are UTC.
Servers that expose MCP over Streamable HTTP to clients you do not fully trust are exposed, including those behind an auth layer that runs before the SDK only if that layer does not limit body size. A body parser such as express.json() does not fix it because it does not limit batch length. Stdio-only servers are not affected.
| Product | Ecosystem | Affected | Fixed in |
|---|---|---|---|
| @modelcontextprotocol/sdk | npm | >= 1.10.0, < 1.30.1 | 1.30.1 |
| @modelcontextprotocol/server | npm | >= 2.0.0, < 2.1.0 | 2.1.0 |
| @modelcontextprotocol/node | npm | >= 2.0.0, < 2.1.0 | 2.1.0 |
| @modelcontextprotocol/hono | npm | >= 2.0.0, < 2.0.1 | 2.0.1 |
npm ls @modelcontextprotocol/sdk @modelcontextprotocol/server @modelcontextprotocol/node @modelcontextprotocol/hono and compare against the affected ranges@modelcontextprotocol/sdk to 1.30.1 or later on the 1.x line@modelcontextprotocol/server, @modelcontextprotocol/node to 2.1.0 or later on the 2.x line@modelcontextprotocol/hono to 2.0.1 or latermaxRequestBodySize option; or cap request body size in a reverse proxy until upgradedEach row is the first time that source carried this signal. The analyst’s rows are its own findings.
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.
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 2.0.0Upgrade to:
@modelcontextprotocol/sdk 1.30.1 or later@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.
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