WordPress 5.4.2 has been available from the 10th of June, but what are the main features of this new release?

This version integrates new security and maintenance features.
Among them, a number of bugs related to XSS issues affecting JavaScripts and theme ahve been fixed, together with an open direct issue in wp_validate_redirect() and an issue with comments on password-protected posts and pages.

Check the whole list here.