GutenKit 2.5.0 - 2.5.4 - Author+ Stored XSS via Page Settings Custom CSS

The GutenKit WordPress plugin before 2.5.5 does not properly sanitize custom CSS saved against a post before printing it inside an inline style block on the published page, allowing users with the Author role and above to break out of the style element and store JavaScript that executes in the browser of any visitor who views the post. Exploitation affects sites running WordPress below 7.0.