mcp-server-semgrep/semgrep-rules/javascript/express/security/audit/xss/mustache/escape-function-overwrite.yaml

MCP Server for Semgrep Integration - static code analysis with AI

rules:
- id: escape-function-overwrite
  message: >-
    The Mustache escape function is being overwritten. This could bypass
    HTML escaping safety measures built into the rendering engine, exposing
    your application to cross-site scripting (XSS) vulnerabilities. If you
    need unescaped HTML, use the triple brace operator in your template:
    '{{{ ... }}}'.
  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://github.com/janl/mustache.js/#variables
    category: security
    technology:
    - express
    cwe2022-top25: true
    cwe2021-top25: true
    subcategory:
    - audit
    likelihood: LOW
    impact: MEDIUM
    confidence: LOW
  languages:
  - javascript
  - typescript
  severity: WARNING
  pattern-either:
  - pattern: Mustache.escape = ...
  - patterns:
    - pattern-inside: |
        $MUSTACHE = require("mustache");
        ...
    - pattern: $MUSTACHE.escape = ...