mcp-server-semgrep/semgrep-rules/javascript/express/security/cors-misconfiguration.yaml

MCP Server for Semgrep Integration - static code analysis with AI

rules:
- id: cors-misconfiguration
  message: >-
    By letting user input control CORS parameters, there is a risk that software does not properly verify
    that the source
    of data or communication is valid. Use literal values for CORS settings.
  metadata:
    owasp:
    - A07:2021 - Identification and Authentication Failures
    cwe:
    - 'CWE-346: Origin Validation Error'
    category: security
    references:
    - https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS
    technology:
    - express
    subcategory:
    - vuln
    likelihood: MEDIUM
    impact: MEDIUM
    confidence: MEDIUM
  languages:
  - javascript
  - typescript
  severity: WARNING
  mode: taint
  pattern-sources:
  - patterns:
    - pattern-either:
      - pattern-inside: function ... ($REQ, $RES) {...}
      - pattern-inside: function ... ($REQ, $RES, $NEXT) {...}
      - patterns:
        - pattern-either:
          - pattern-inside: $APP.$METHOD(..., function $FUNC($REQ, $RES) {...})
          - pattern-inside: $APP.$METHOD(..., function $FUNC($REQ, $RES, $NEXT) {...})
        - metavariable-regex:
            metavariable: $METHOD
            regex: ^(get|post|put|head|delete|options)$
    - pattern-either:
      - pattern: $REQ.query
      - pattern: $REQ.body
      - pattern: $REQ.params
      - pattern: $REQ.cookies
      - pattern: $REQ.headers
  - patterns:
    - pattern-either:
      - pattern-inside: |
          ({ $REQ }: Request,$RES: Response, $NEXT: NextFunction) =>
          {...}
      - pattern-inside: |
          ({ $REQ }: Request,$RES: Response) => {...}
    - focus-metavariable: $REQ
    - pattern-either:
      - pattern: params
      - pattern: query
      - pattern: cookies
      - pattern: headers
      - pattern: body
  pattern-sinks:
  - patterns:
    - pattern-either:
      - pattern: $RES.set($HEADER, $X)
      - pattern: $RES.header($HEADER, $X)
      - pattern: $RES.setHeader($HEADER, $X)
      - pattern: |
          $RES.set({$HEADER: $X}, ...)
      - pattern: |
          $RES.writeHead($STATUS, {$HEADER: $X}, ...)
    - focus-metavariable: $X
    - metavariable-regex:
        metavariable: $HEADER
        regex: .*(Access-Control-Allow-Origin|access-control-allow-origin).*