The plugin does not validate and escape some of its shortcode attributes before outputting them back in the page, which could allow users with a role as low as contributor to perform Stored Cross-Site Scripting attacks which could be used against high privilege users such as admin.
Insert the following shortcode in a page/post:
[searchandfilter class='" onmouseover="alert(1)"']
The alert triggers successfully when the search form is hovered with the mouse.