Take Advantage of Out-of-Scope Domains in Bug Bounty Programs
Cross Site Scripting (XSS)
In brief, you may be able to escalate your attacks by using API’s, javacript workarounds, a misconfiguration on a domain that isn’t under the program scope.
https://ahussam.me/Take-Advantage-of-Out-of-Scope-Domains-in-Bug-Bounty/