Kirki – Freeform Page Builder, Website Builder & Customizer <= 6.3.1 - Authenticated (Subscriber+) Arbitrary Shortcode Execution via 'display_name'

The Kirki – Freeform Page Builder, Website Builder & Customizer plugin for WordPress is vulnerable to arbitrary shortcode execution in all versions up to, and including, 6.3.1 This is due to the plugin substituting a user's `display_name` into the composed page markup unfiltered and then running the whole result through `do_shortcode()` in `TheFrontend::replace_content()`. Because `display_name` is writable by any user on their own account through the core profile form, this makes it possible for authenticated attackers with Subscriber-level access and above to execute arbitrary shortcodes. Where the page is a users collection — an ordinary team or member-directory page — the shortcode runs in the request of every visitor, including unauthenticated ones. Requires a published page with a Kirki element whose dynamic content is bound to the `display_name` user field.