Using a javascript: URI with a setTimeout race condition, an attacker can execute unauthorized scripts on top origin sites in urlbar. This bypasses security measures, potentially leading to arbitrary code execution or unauthorized actions within the user's loaded webpage.

An attacker could execute unauthorized script on a legitimate site through UXSS using window.open() by opening a javascript URI leading to unauthorized actions within the user's loaded webpage.

An attacker could have executed unauthorized scripts on top origin sites using a JavaScript URI when opening an external URL with a custom Firefox scheme and a timeout race condition.