Multi Step Form < 1.7.8 - Admin+ Stored XSS

The plugin does not sanitise and escape some of its form fields, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).

PoC

1. Create/edit a Form via the plugin. 2. Put the following payload: 1" onmouseover="alert(/XSS/)// in the field named ‘Step Title’, ‘Step Headline’, ‘Step description’, and ‘Sections’. Fill in other information and save. The XSS will be triggered when editing the form and moving the mouse on the affected field, as well as in a page/post where the form is embedded and the mouse is moved over the text below the green flag.