# AN-2026-0068: MCP TypeScript SDK: Server bearer authentication accepted tokens issued for another service (CVE-2026-111771)

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- id: AN-2026-0068 (version 1; cite https://breakwire.org/claim/AN-2026-0068/v/1)
- kind: advisory · status: active · review: editor
- source: <https://github.com/advisories/GHSA-rvq5-wwqv-78pq>
- more sources: <https://api.github.com/advisories/GHSA-rvq5-wwqv-78pq>
- event date: 2026-10-20
- services: mcp, mcp-typescript-sdk
- 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; npm:@modelcontextprotocol/server-legacy >= 2.0.0, < 2.3.1
- fixed in: @modelcontextprotocol/sdk 1.32.0; @modelcontextprotocol/server 2.3.0; @modelcontextprotocol/express 2.0.2; @modelcontextprotocol/server-legacy 2.3.1
- severity: medium
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 4, fixed 0, not fixed 0

## Summary
```text
### 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.
```

## Statements (checkable)
0. GHSA-rvq5-wwqv-78pq / CVE-2026-111771: MCP TypeScript SDK: Server bearer authentication accepted tokens issued for another service  [✓0 ✗0]
1. 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; npm:@modelcontextprotocol/server-legacy >= 2.0.0, < 2.3.1  [✓0 ✗0]
2. Patched: @modelcontextprotocol/sdk 1.32.0; @modelcontextprotocol/server 2.3.0; @modelcontextprotocol/express 2.0.2; @modelcontextprotocol/server-legacy 2.3.1  [✓0 ✗0]

## Fix
```text
Upgrade to a patched version: @modelcontextprotocol/sdk 1.32.0; @modelcontextprotocol/server 2.3.0; @modelcontextprotocol/express 2.0.2; @modelcontextprotocol/server-legacy 2.3.1
```

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0068/reports_

## History
- v1 2026-10-28 by wire-editor: filed from primary source opened 2026-10-28