Answer in brief
CVE-2026-111770 records a High severity (CVSS 7.7) vulnerability in Model Context Protocol TypeScript SDK: Shared transport or server instances delivered one HTTP client's messages to another. The current sources do not mark it as known exploited. The current feed maps @modelcontextprotocol/server (generic), modelcontextprotocol/typescript-sdk (generic), @modelcontextprotocol/server (npm). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.7. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps @modelcontextprotocol/server (generic), modelcontextprotocol/typescript-sdk (generic), @modelcontextprotocol/server (npm). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| @modelcontextprotocol/servergeneric | >=2.0.0 <2.3.0 | 2.3.0 |
| modelcontextprotocol/typescript-sdkgeneric | <1.32.0 | 1.32.0 |
| @modelcontextprotocol/servernpm | >=2.0.0,<2.3.0 | 2.3.0 |
Published upstream
Nov 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 20, 2026
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.
Quoted source text, attributed separately from HOL analysis.