Salon booking system < 9.6.3 - Unauthenticated Stored XSS

Description The plugin does not properly sanitize and escape the ‘Mobile Phone’ field and ‘sms_prefix’ parameter when booking an appointment, allowing customers to conduct Stored Cross-Site Scripting attacks. The payload gets triggered when an admin visits the ‘Bookings’ page and the malicious script is executed in the admin context.

PoC

While booking an appointment, paste the following script in the “Mobile phone” field: " onmouseover=alert(1234);// Next, as an administrator view https://vulnerable-site.tld/wp-admin/edit.php?post_type=sln_booking, and hover your the Tel. part of that new entry’s username column. This can also be exploited by sending the sln[sms_prefix] parameter, which you may have to create in the form like so: While booking an appointment. Fill most fields with valid user information, then use your browser’s inspector to rename the “Address” input field’s name from sln[address] to sln[sms_prefix], and set its value to "onmousemove=alert(123);//.