CVE-2026-111770: Model Context Protocol TypeScript SDK Multi-Client Message Routing Flaw

# CVE-2026-111770: Model Context Protocol TypeScript SDK Multi-Client Message Routing Flaw

https://gcdradar.vercel.app/incidents/cve-2026-111770-model-context-protocol-typescript-sdk-multi · AIR-2026-1794 · closed 2026-11-05

- Lane: Research
- Severity: 2 (Disclosed vulnerability): Disclosed vulnerability with a vendor advisory and patch status.
- Fix status: Fix status unknown
- First reported: 2026-11-05
- AI role: Attack on AI
- Products: Model Context Protocol TypeScript SDK
- CVE ids: CVE-2026-111770
- CVSS: 7.7

## Summary

Applications sharing a stateless HTTP transport or server instance among multiple clients in the Model Context Protocol TypeScript SDK could deliver responses to the wrong client. The vulnerability stems from associating messages solely with JSON-RPC request identifiers.

## What to do

Update to version 2.3.0 or later.

## Affected and fixed versions

- Affected: @modelcontextprotocol/server >= 2.0.0, < 2.3.0
- Fixed in: @modelcontextprotocol/server 2.3.0

## Latest updates

- 2026-11-05: CVE-2026-111770: The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. (https://nvd.nist.gov/vuln/detail/CVE-2026-111770)

## Sources

- 2026-11-05 NVD: CVE-2026-111770: The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. https://nvd.nist.gov/vuln/detail/CVE-2026-111770

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.