Bold Page Builder <= 5.7.2 - Authenticated (Contributor+) Stored Cross-Site Scripting via bt_bb_css_image_grid 'images' Shortcode Attribute

The Bold Page Builder plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'images' parameter of the plugin's bt_bb_css_image_grid shortcode in all versions up to, and including, 5.7.2 due to insufficient input sanitization and output escaping on user-supplied attributes. This makes it possible for authenticated attackers, with Contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.