Model Context Protocol TypeScript SDK 出現可造成拒絕服務的 GHSA-f897-62hf-6gxq 漏洞

GHSA-f897-62hf-6gxq: Unbounded Request Body and JSON-RPC Batch DoS in Model Context Protocol TypeScript SDK

Vulnerability ID: GHSA-F897-62HF-6GXQ
CVSS Score: 7.5
Published: 2026-10-27

The Model Context Protocol (MCP) TypeScript SDK contains an uncontrolled resource consumption vulnerability in its HTTP server transport implementations and middleware adapters. Affected versions fail to enforce upper bounds on incoming HTTP POST request body sizes and JSON-RPC 2.0 batch array lengths. In addition, middleware wrappers for Express and Hono parse request bodies into memory prior to validating Host and Origin headers. Unauthenticated remote attackers can exploit these flaws to trigger Out-Of-Memory (OOM) process crashes or monopolize the single-threaded Node.js event loop.

TL;DR

Unbounded HTTP request body buffering and unrestricted JSON-RPC batch array lengths in the MCP TypeScript SDK allow remote unauthenticated attackers to cause Denial of Service via memory exhaustion or Node.js event loop starvation.

⚠️ Exploit Status: POC

Technical Details

Advisory ID: GHSA-f897-62hf-6gxq
Weakness Class: CWE-400 (Uncontrolled Resource Consumption) / CWE-770
Attack Vector: Network (HTTP POST over Streamable HTTP / Express / Hono / Node)
CVSS v3.1 Score: 7.5 High (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Primary Impact: Denial of Service (V8 Heap OOM Crash & Event Loop Starvation)
Default Limits Added: 4 MiB Max Request Body Size / 100 Max JSON-RPC Batch Length
Exploit Status: PoC (Reproduced via unit tests and HTTP streaming scripts)
KEV Status: Not Listed

Affected Systems

@modelcontextprotocol/sdk
@modelcontextprotocol/server
@modelcontextprotocol/node
@modelcontextprotocol/hono
@modelcontextprotocol/express
@modelcontextprotocol/sdk: >= 1.10.0, < 1.30.1 (Fixed in: 1.30.1)
@modelcontextprotocol/server: = 2.0.0 (Fixed in: 2.1.0)
@modelcontextprotocol/node: = 2.0.0 (Fixed in: 2.1.0)
@modelcontextprotocol/hono: = 2.0.0 (Fixed in: 2.0.1)

Code Analysis

Commit: 7b781ed

Enforce request body size limits, JSON-RPC batch length caps, and middleware ordering in v2.x branch (PR #2698)

Commit: a9f6eb7

Backport request body size limits, JSON-RPC batch length caps, and middleware ordering to v1.x branch (PR #2717)

Mitigation Strategies

Upgrade MCP TypeScript SDK packages to patched releases that enforce a 4 MiB default body limit and a 100-message JSON-RPC batch cap.
Enforce strict HTTP request body size limits (e.g., client_max_body_size 4M) and connection rate limiting at the upstream reverse proxy or WAF layer.
Require authentication at the network edge or API gateway prior to routing traffic to MCP HTTP server endpoints.

Remediation Steps:

For v1.x deployments, run: npm install @modelcontextprotocol/sdk@>=1.30.1
For v2.x deployments, run: npm install @modelcontextprotocol/server@>=2.1.0 @modelcontextprotocol/node@>=2.1.0 @modelcontextprotocol/hono@>=2.0.1
Verify custom Express or Hono middleware stacks to ensure Host, Origin, and authentication checks execute prior to any body-parsing middleware.
Configure Nginx or ingress controllers with client_max_body_size 4M; to drop oversized requests before they reach the Node.js application.

References

Read the full report for GHSA-F897-62HF-6GXQ on our website for more details including interactive diagrams and full exploit analysis.