Navigate to WP Ticket > Forms >  edit layout of "Open a Ticket" or "Search Tickets" > on "Editing Form" Setting menu.

Select a form field and you can edit the "Label" with a cross-site scripting (XSS) payload such as
v < 5.10.3 - "><script>alert(/XSS/)</script> 
v <= 5.10.3 - " style=animation-name:rotation onanimationstart=alert(/XSS/)//

All of the parameters on the "Editing Form" are vulnerable.

To trigger the XSS payload, refresh the "Editing Form" page.