mcp-server-semgrep/semgrep-rules/python/flask/security/xss/audit/direct-use-of-jinja2.yaml

MCP Server for Semgrep Integration - static code analysis with AI

rules:
- id: direct-use-of-jinja2
  message: >-
    Detected direct use of jinja2. If not done properly,
    this may bypass HTML escaping which opens up the application to
    cross-site scripting (XSS) vulnerabilities. Prefer using the Flask
    method 'render_template()' and templates with a '.html' extension
    in order to prevent XSS.
  metadata:
    cwe:
    - "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')"
    owasp:
    - A07:2017 - Cross-Site Scripting (XSS)
    - A03:2021 - Injection
    references:
    - https://jinja.palletsprojects.com/en/2.11.x/api/#basics
    category: security
    technology:
    - flask
    cwe2022-top25: true
    cwe2021-top25: true
    subcategory:
    - audit
    likelihood: LOW
    impact: MEDIUM
    confidence: LOW
  languages:
  - python
  severity: WARNING
  pattern-either:
  - pattern: jinja2.Environment(...)
  - pattern: jinja2.Template.render(...)
  - patterns:
    - pattern-inside: |
        $TEMPLATE = $ENV.get_template(...)
        ...
    - pattern: $TEMPLATE.render(...)
  - patterns:
    - pattern-inside: |
        $TEMPLATE = jinja2.Template(...)
        ...
    - pattern: $TEMPLATE.render(...)