WordPress 4.5.3 is now available for download and is a security release for all previous versions. It is highly recommended that you update your sites immediately. There are also a number of bug fixes which apply to WordPress versions 4.5, 4.5.1 and 4.5.2.
More information on the update is available: https://wordpress.org/news/2016/06/wordpress-4-5-3/
Full list of changes: https://core.trac.wordpress.org/query?milestone=4.5.3
If you have not done so already – download the update or simply use your existing installation of WordPress to update your site. Either way – this is an excellent time to make a backup copy of your site(s) before upgrading.