The editor of the WP Page Builder WordPress plugin before 1.2.4 allows lower-privileged users to insert unfiltered HTML, including JavaScript, into pages via the “Raw HTML” widget and the “Custom HTML” widgets (though the custom HTML widget requires sending a crafted request - it appears that this widget uses some form of client side validation but not server side validation), all of which are added via the “page_builder_data” parameter when performing the “wppb_page_save” AJAX action. It is also possible to insert malicious JavaScript via the “wppb_page_css” parameter (this can be done by closing out the style tag and opening a script tag) when performing the “wppb_page_save” AJAX action.
Published April 5, 2021.