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  • AgentArmor teamTeam3d agoNeeds helpSolved

    Am I affected by MCP TypeScript SDK accepted bearer tokens issued for another service? What should I do?

    The SDK's server-side bearer authentication had no way to check that a token was issued for your server (its audience).

    Affected: @modelcontextprotocol/sdk 1.6.0 to 1.31.0; @modelcontextprotocol/server 2.0.0 to 2.2.0; @modelcontextprotocol/express 2.0.0 to 2.0.1; @modelcontextprotocol/server-legacy 2.0.0 to 2.3.0. Fixed in: @modelcontextprotocol/sdk 1.32.0, @modelcontextprotocol/server 2.3.0, @modelcontextprotocol/express 2.0.2, @modelcontextprotocol/server-legacy 2.3.1. What should you check, and what should you do about it?

    Full incident page with sources: https://agentarmorhq.com/incidents/2026/10/cve-2026-111771-mcp-typescript-sdk-modelcontextprotocol-packages (opens external site)

    1 answer

    • Best answerAgentArmor teamTeamIncidents, compromised packages and supply chain3d ago

      Am I affected? Affected: @modelcontextprotocol/sdk 1.6.0 to 1.31.0; @modelcontextprotocol/server 2.0.0 to 2.2.0; @modelcontextprotocol/express 2.0.0 to 2.0.1; @modelcontextprotocol/server-legacy 2.0.0 to 2.3.0. Fixed in: @modelcontextprotocol/sdk 1.32.0, @modelcontextprotocol/server 2.3.0, @modelcontextprotocol/express 2.0.2, @modelcontextprotocol/server-legacy 2.3.1.

      • Check your version: run npm ls @modelcontextprotocol/sdk. Versions >= 1.6.0, < 1.32.0 of @modelcontextprotocol/sdk are affected.
      • Check your version: run npm ls @modelcontextprotocol/server. Versions >= 2.0.0, < 2.3.0 of @modelcontextprotocol/server are affected.
      • Check your version: run npm ls @modelcontextprotocol/express. Versions >= 2.0.0, < 2.0.2 of @modelcontextprotocol/express are affected.

      What to do now

      1. Upgrade to the fixed version: run npm install @modelcontextprotocol/sdk@1.32.0 (first patched version 1.32.0).
      2. Upgrade to the fixed version: run npm install @modelcontextprotocol/server@2.3.0 (first patched version 2.3.0).
      3. Upgrade to the fixed version: run npm install @modelcontextprotocol/express@2.0.2 (first patched version 2.0.2).
      4. Upgrade to @modelcontextprotocol/sdk 1.32.0 or later, @modelcontextprotocol/server 2.3.0 or later (with @modelcontextprotocol/express 2.0.2 or later if you use it), or @modelcontextprotocol/server-legacy 2.3.1 or later.
      5. Upgrading alone changes nothing: also pass expectedResource to requireBearerAuth() and return the token's audience from verifyAccessToken() as AuthInfo.resource.
      6. If you cannot upgrade yet, reject any token whose aud does not include your server inside verifyAccessToken().

      General practice, not from the source: if the affected software could read tokens or credentials, rotate them after upgrading; pin versions and review changes before updating tools your agents run.

      Sources

      Full incident page: https://agentarmorhq.com/incidents/2026/10/cve-2026-111771-mcp-typescript-sdk-modelcontextprotocol-packages (opens external site)

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