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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-111770
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-05 22:17:45 UTC
Updated2026-11-05 22:17:45 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v3.1 7.7 HIGH from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H

Problem Types: CWE-362 | CWE-362 CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.7HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H
3.1CNADECLARED7.7HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Modelcontextprotocol Typescript-sdk affected < 1.32.0 Not specified
CNA @modelcontextprotocol Server affected >= 2.0.0, < 2.3.0 Not specified

References

ReferenceSourceLinkTags
github.com/modelcontextprotocol/typescript-sdk/releases/tag/1.32.0 [email protected] github.com
github.com/modelcontextprotocol/typescript-sdk/pull/2918 [email protected] github.com
github.com/modelcontextprotocol/typescript-sdk/commit/84804c22e45a662675... [email protected] github.com
github.com/modelcontextprotocol/typescript-sdk/releases/tag/@modelcontex... [email protected] github.com
github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-... [email protected] github.com
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