In the Elementor Website Builder WordPress plugin before 3.1.4, the heading widget (includes/widgets/heading.php) accepts a ??header_size?? parameter. Although the element control lists a fixed set of possible html tags, it is possible for a user with Contributor or above permissions to send a modified ??save_builder?? request with this parameter set to ??script?? and combined with a ??title?? parameter containing JavaScript, which will then be executed when the saved page is viewed or previewed.
