1) Sign in to your paypal account
2) Go to category: Tools > Forms of Payment
3) Click on Create a new payment format
4) Complete the form and click Submit
5) Go to: Manage payment formats > Edit the created payment format >
6) Memo or "Reminder Note" > Edit > Here we insert our payload, i.e: "><img src=x on error=prompt(document.domain)> > Click on Saved
7) The XSS will be executed successfully.