WordPress 5.0.3 fixes 36 bugs and 7 performance updates.
Things to note
Most of the updates/fixes were related to the block editor and Customizer.
You can read more by looking at the release notes: https://codex.wordpress.org/Version_5.0.3
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.