The Rezgo Online Booking WordPress plugin before 4.1.8 does not sanitise and escape some parameters before outputting them back in a page, leading to a Reflected Cross-Site Scripting, which can be exploited either via a LFI in an AJAX action, or direct call to the affected file
https://wpscan.com/vulnerability/005c2300-f6bd-416e-97a6-d42284bbb093