mcp-server-semgrep/semgrep-rules/javascript/express/security/audit/express-path-join-resolve-traversal.yaml

MCP Server for Semgrep Integration - static code analysis with AI

rules:
- id: express-path-join-resolve-traversal
  message: >-
    Possible writing outside of the destination,
    make sure that the target path is nested in the intended destination
  metadata:
    owasp:
    - A05:2017 - Broken Access Control
    - A01:2021 - Broken Access Control
    cwe:
    - "CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')"
    category: security
    references:
    - https://owasp.org/www-community/attacks/Path_Traversal
    technology:
    - express
    - node.js
    cwe2022-top25: true
    cwe2021-top25: true
    subcategory:
    - vuln
    likelihood: HIGH
    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:
    - focus-metavariable: $SINK
    - pattern-either:
      - pattern-inside: |
          $PATH = require('path');
          ...
      - pattern-inside: |
          import $PATH from 'path';
          ...
    - pattern-either:
      - pattern: $PATH.join(...,$SINK,...)
      - pattern: $PATH.resolve(...,$SINK,...)
  - patterns:
    - focus-metavariable: $SINK
    - pattern-inside: |
        import 'path';
        ...
    - pattern-either:
      - pattern: path.join(...,$SINK,...)
      - pattern: path.resolve(...,$SINK,...)
  pattern-sanitizers:
  - pattern: $Y.replace(...)
  - pattern: $Y.indexOf(...)
  - pattern: |
      function ... (...) {
          ...
          <... $Y.indexOf(...) ...>
          ...
      }
  - patterns:
    - pattern: $FUNC(...)
    - metavariable-regex:
        metavariable: $FUNC
        regex: sanitize