Answer in brief
CVE-2026-111771 records a Medium severity (CVSS 6.8) vulnerability in Model Context Protocol TypeScript SDK: Server bearer authentication accepted tokens issued for another service. The current sources do not mark it as known exploited. The current feed maps @modelcontextprotocol/express (generic), @modelcontextprotocol/sdk (generic), @modelcontextprotocol/server (generic), @modelcontextprotocol/server-legacy (generic) and additional mapped packages. 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 6.8. 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/express (generic), @modelcontextprotocol/sdk (generic), @modelcontextprotocol/server (generic), @modelcontextprotocol/server-legacy (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| @modelcontextprotocol/expressgeneric | >=2.0.0 <2.0.2 | 2.0.2 |
| @modelcontextprotocol/sdkgeneric | >=1.6.0 <1.32.0 | 1.32.0 |
| @modelcontextprotocol/servergeneric | >=2.0.0 <2.3.0 | 2.3.0 |
| @modelcontextprotocol/server-legacygeneric | >=2.0.0 <2.3.1 | 2.3.1 |
| modelcontextprotocol/typescript-sdkgeneric | >=1.6.0 <1.32.0 | 1.32.0 |
| @modelcontextprotocol/expressnpm | >=2.0.0,<2.0.2 | 2.0.2 |
| @modelcontextprotocol/sdknpm | >=1.6.0,<1.32.0 | 1.32.0 |
| @modelcontextprotocol/servernpm | >=2.0.0,<2.3.0 | 2.3.0 |
| @modelcontextprotocol/server-legacynpm | >=2.0.0,<2.3.1 | 2.3.1 |
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 1.6.0 until 1.32.0 in @modelcontextprotocol/sdk, from 2.0.0 until 2.3.0 in @modelcontextprotocol/server, from 2.0.0 until 2.0.2 in @modelcontextprotocol/express, and from 2.0.0 until 2.3.1 in @modelcontextprotocol/server-legacy, server-side bearer authentication could accept a valid access token issued for a different service because the SDK did not enforce the token audience. The affected surface is server-side HTTP bearer authentication. The trigger is a valid token whose audience names another service. The authorization server must issue tokens for multiple services, and the application's verifyAccessToken() must not independently validate aud. Applications already validating aud inside verifyAccessToken() are not affected. An attacker with a token for another service could authenticate to the MCP server and obtain the confidentiality and integrity capabilities granted to an authenticated caller. Upgrading alone leaves the new audience validation disabled. Operators must enable audience validation and provide the token audience together. Enabling only the expected audience check causes every request to receive HTTP 401. This issue is fixed in @modelcontextprotocol/sdk 1.32.0, @modelcontextprotocol/server 2.3.0, @modelcontextprotocol/express 2.0.2, and @modelcontextprotocol/server-legacy 2.3.1.
Quoted source text, attributed separately from HOL analysis.