Check origin of events

Metadata

ID: javascript-browser-security/event-check-origin

Language: JavaScript

Severity: Warning

Category: Security

Description

Not checking the rule origin can lead to XSS attacks. Always check the event origin.

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Non-Compliant Code Examples

window.addEventListener('message', (event) => {
  processing();
})

Compliant Code Examples

window.addEventListener('message', (event) => {
  if (event.origin != 'https://app.domain.tld') {
    throw new Error('invalid origin')
  }

  processing();
})