CVE-2026-111771: MCP TypeScript SDK: Server bearer authentication accepted tokens issued for another service
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.
References
- github.com/advisories/GHSA-rvq5-wwqv-78pq
- github.com/modelcontextprotocol/typescript-sdk/commit/40f8f4e229d963cd7fd2890bda2aeebe7005299a
- github.com/modelcontextprotocol/typescript-sdk/commit/5a0724d14cf34a27a3b070224d2996cdd611df9f
- github.com/modelcontextprotocol/typescript-sdk/commit/5a1867390b91b8836f49af76c45427279f513325
- github.com/modelcontextprotocol/typescript-sdk/security/advisories/GHSA-rvq5-wwqv-78pq
- nvd.nist.gov/vuln/detail/CVE-2026-111771
Code Behaviors & Features
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