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

What to know

What it is: 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…
Affected: @modelcontextprotocol/sdk (npm) >= 1.10.0, < 1.30.1; @modelcontextprotocol/server (npm) >= 2.0.0, < 2.1.0; @modelcontextprotocol/node (npm) >= 2.0.0, < 2.1.0; @modelcontextprotocol/hono (npm) >= 2.0.0, < 2.0.1
Fix: Upgrade @modelcontextprotocol/sdk to 1.30.1; @modelcontextprotocol/server to 2.1.0; @modelcontextprotocol/node to 2.1.0; @modelcontextprotocol/hono to 2.0.1 or later.
Exploitation: No known exploitation

Story map

Story map: the flaws, the fix, how it unfolded and what it connects to. Boxes link to the record or article.

At a glance

@modelcontextprotocol/sdk: Amber, patch this week. The MCP TypeScript SDK's experimental tasks feature did not check which session created a task, allowing clients to list, read, and cancel each other's tasks. An attacker could exploit this vulnerability to gain control over other clients' tasks.

The flaws

GHSA-f897-62hf-6gxq: MCP TypeScript SDK: HTTP server transports and handlers did not limit request body size or JSON-RPC batch length (CVSS 7.5)
CVE-2026-111767: MCP TypeScript SDK: Experimental tasks were not tied to the session that created them (CVSS 8.6 · EPSS 0%)
CVE-2026-104850: MCP TypeScript SDK: OAuth client could send credentials to an authorization server chosen by the MCP server (CVSS 7.5 · EPSS 0%)
CVE-2026-111768: MCP TypeScript SDK: One HTTP request within the default size limit could exhaust server memory during validation (CVSS 7.5)

The fix

Upgrade @modelcontextprotocol/sdk: 1.32.0 · 1.31.0 · 2.2.0 or later on your release line

Who is exposed: {'products': ['MCP TypeScript SDK'], 'packages': [{'ecosystem': 'npm', 'name': '@modelcontextprotocol/sdk', 'vulnerable': '>= 1.24.0, < 1.32.0', 'patched': '1.32.0'}], 'versions': ['1.24.0 to 1.32.0 (exclusive)', '1.32.0']}

Where it stands

No known exploitation

Connects to

Same weakness: Denial of service (CWE-770). 225 other warnings in 30 days

Why it is Yellow

CVSS 7.5 high
Remotely exploitable without logging in
On your watchlist: npm

Affected packages

Package	Ecosystem	Vulnerable	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

References

Original 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.