rules:
  - id: auth.mcp.unauthenticated-server
    languages:
      - javascript
      - typescript
    severity: ERROR
    message: |
      This MCP transport is mounted on an Express route with NO auth middleware.
      The tools are reachable unauthenticated (CWE-306). The route passes only
      (path, handler): there is no `requireBearerAuth(...)` in the chain, so any
      caller can drive the MCP server. A Knostic scan found none of ~2,000
      internet-exposed MCP servers required auth.

      Put `requireBearerAuth(...)` before the transport handler:
        const auth = requireBearerAuth({ verifier, resourceMetadataUrl });
        app.post('/mcp', auth, async (req, res) => { await transport.handleRequest(req, res, req.body); });
    # A route with only (path, handler) has no middleware; adding requireBearerAuth
    # would make it (path, middleware, handler), which these patterns do NOT match.
    # Scoped to handlers that actually dispatch the MCP transport (.handleRequest /
    # toNodeHandler / createMcpHandler), so ordinary routes don't trip.
    pattern-either:
      # (a) a handler that dispatches the MCP transport, inside a 2-arg Express
      #     route (verb, path, handler), i.e. no requireBearerAuth middleware.
      #     Scoped to real HTTP verbs so an ordinary 2-arg method call (e.g. the
      #     SDK's own `transport.handleRequest(req, opts)`) is NOT matched.
      - patterns:
          - pattern: $T.handleRequest(...)
          - pattern-either:
              - pattern-inside: '$APP.get($PATH, $HANDLER)'
              - pattern-inside: '$APP.post($PATH, $HANDLER)'
              - pattern-inside: '$APP.put($PATH, $HANDLER)'
              - pattern-inside: '$APP.delete($PATH, $HANDLER)'
              - pattern-inside: '$APP.patch($PATH, $HANDLER)'
              - pattern-inside: '$APP.all($PATH, $HANDLER)'
          - pattern-not-inside: '$APP.$V($PATH, requireBearerAuth(...), $HANDLER)'
      # (b) the v2 node/mcp handler mounted directly on a route with no middleware.
      - pattern-either:
          - pattern: '$APP.get($PATH, toNodeHandler(...))'
          - pattern: '$APP.post($PATH, toNodeHandler(...))'
          - pattern: '$APP.all($PATH, toNodeHandler(...))'
          - pattern: '$APP.get($PATH, createMcpHandler(...))'
          - pattern: '$APP.post($PATH, createMcpHandler(...))'
          - pattern: '$APP.all($PATH, createMcpHandler(...))'
    metadata:
      oauthlint-rule-id: AUTH-MCP-003
      oauthlint-doc-url: https://oauthlint.dev/rules/mcp-unauthenticated-server
      category: security
      cwe: CWE-306
      owasp: API2:2023
      llm-prevalence: HIGH
      technology:
        - mcp
        - modelcontextprotocol
      references:
        - https://modelcontextprotocol.io/specification/2026-07-28/basic/authorization
        - https://healthsystemcio.com/2026/07/28/mcp-server-exposure-health-isac/