Elementor Website Builder <= 3.1.3 - Authenticated (Contributor+) Stored Cross-Site Scripting via title_size

In the Elementor Website Builder WordPress plugin before 3.1.4, the image box widget (includes/widgets/image-box.php) accepts a ‘title_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 containing JavaScript in the ‘title_size’ parameter, which is not filtered and is output without escaping. This JavaScript will then be executed when the saved page is viewed or previewed.