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CVE-2026-111770— Model Context Protocol TypeScript SDK: Shared transport or server instances delivered one HTTP client's messages to another

Quick assessment

Affected
modelcontextprotocol typescript-sdk
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Model Context Protocol（MCP）TypeScript SDK 提供了该协议的 TypeScript 客户端与服务器实现。在 从 2.0.0 到 2.3.0 的版本中，若多个客户端共享同一个无状态 HTTP 传输层、同一个 或 实例，应用可能将响应和通知错误地发送给其他客户端。受影响的场景是通过 HTTP 协议由多个客户端访问的 MCP 服务器。触发条件为复用了同一个无状态传输层或服务器实例。 该漏洞的根源在于：消息仅通过 JSON-RPC 请求标识符（request identifier）与连

CVSS 7.7 · High
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I. Basic Information for CVE-2026-111770

Vulnerability Information
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Vulnerability Title
Model Context Protocol TypeScript SDK: Shared transport or server instances delivered one HTTP client's messages to another
Source: CVE Program / CVE List V5
Vulnerability Description
The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. From 2.0.0 until 2.3.0 in @modelcontextprotocol/server, applications that shared one stateless HTTP transport or one McpServer or Server instance among multiple clients could deliver responses and notifications to the wrong client. The affected surface is an MCP server reached over HTTP by multiple clients. The trigger is reuse of one stateless transport or server instance. Messages were associated with a connection using only the JSON-RPC request identifier. SDK clients start request identifiers at zero, so collisions occur in normal operation. Cross-client delivery exposes one client's responses and notifications to another client. The issue requires an HTTP endpoint reachable by more than one client and an application that constructs the server or transport once at startup instead of once per request or session. stdio servers and factory-created per-call servers are not affected. Upgrading causes reused instances to fail and therefore requires an application code change. This issue is fixed in @modelcontextprotocol/server 2.3.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
使用共享资源的并发执行不恰当同步问题(竞争条件)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
modelcontextprotocol typescript-sdk < 1.32.0 -
@modelcontextprotocol server >= 2.0.0, < 2.3.0 -

II. Public POCs for CVE-2026-111770

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III. Intelligence Information for CVE-2026-111770

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Other References for CVE-2026-111770 (5)

Same Patch Batch · modelcontextprotocol · 2026-11-05 · 4 CVEs total

CVE-2026-111768 7.5 HIGH Model Context Protocol TypeScript SDK: One HTTP request within the default size limit coul
CVE-2026-111771 6.8 MEDIUM Model Context Protocol TypeScript SDK: Server bearer authentication accepted tokens issued
CVE-2026-111769 6.5 MEDIUM Model Context Protocol TypeScript SDK: HTTP client transports and OAuth requests followed

IV. Related Vulnerabilities

Same product: typescript-sdk
Same vendor: modelcontextprotocol
Same weakness: CWE-362