The Visual Composer plugin for WordPress (80,000+ active installations) fixed multiple stored XSS vulnerabilities affecting version 26.0 and below.
The WordPress Login/Signup Popup plugin, which has 10,000+ active installations, fixed a zero-day vulnerability affecting version 1.4 and below.
The Elementor Pro plugin for WordPress is prone to a critical zero-day vulnerability affecting version 2.9.3 and below.
Elementor Page Builder (4+ million installations), was prone to a broken access control vulnerability affecting version 2.9.7 and below that could lead to stored XSS vulnerability via SVG image upload.
Avada WordPress Theme (600,000 installations) fixed multiple critical vulnerabilities affecting version 6.2.2 and below.