MEDIUM 6.8 GitHub
CVE-2026-111771
MCP TypeScript SDK: Server bearer authentication accepted tokens issued for another service
### Summary
In affected versions, the SDK's server-side bearer authentication had no way to check that a token was issued for your server (its audience). Where one authorization server issues tokens for several services, a valid token for another service was also accepted by your MCP server.
### Am I affected?
Yes, if your HTTP server uses `requireBearerAuth()` or `verifyBearerToken()`, its authorization server also issues tokens for other services, and your `verifyAccessToken()` does not check
Affected Products
- npm/@modelcontextprotocol/sdk >= 1.6.0, < 1.32.0
- npm/@modelcontextprotocol/server >= 2.0.0, < 2.3.0
- npm/@modelcontextprotocol/express >= 2.0.0, < 2.0.2
- npm/@modelcontextprotocol/server-legacy >= 2.0.0, < 2.3.1
References
- https://github.com/advisories/GHSA-rvq5-wwqv-78pq
- https://github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-rvq5-wwqv-
- https://github.com/modelcontextprotocol/typescript-sdk/commit/40f8f4e229d963cd7fd2890bda2a
- https://github.com/modelcontextprotocol/typescript-sdk/commit/5a0724d14cf34a27a3b070224d29
This medium severity vulnerability with a CVSS score of 6.8 was published on 2026-10-20 via GitHub. Affected: npm/@modelcontextprotocol/sdk >= 1.6.0, < 1.32.0, npm/@modelcontextprotocol/server >= 2.0.0, < 2.3.0, npm/@modelcontextprotocol/express >= 2.0.0, < 2.0.2 and 1 more.
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