CVE-2026-111770

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, service disruption.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-10-16 17:52 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-11-05 22:17 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-11-05 22:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 7.7 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-11-05 22:17 UTC

Last modified

2026-11-05 22:17 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-362 · Race condition

Record status

Received

Attack profile CVSS 3.1 · 7.7

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

Low

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-111770.md and follow it. Check whether this project is affected by CVE-2026-111770. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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