This is an urgent security release and we recommend you update your website as soon as possible!
WordPress versions 4.2.2 and earlier are effected by this vulnerability. 4.2.3 fixes a vulnerability which allowed users with the roles of Contributor or Author to compromise the site, as well as a vulnerability which allowed Subscribers to create a draft.
WordPress 4.2.3 also contains fixes for 20 bugs from 4.2.
Download WordPress 4.2.3 or venture over to Dashboard → Updates and simply click “Update Now.” Sites that support automatic background updates are already beginning to update to WordPress 4.2.3. – WordPress
If you would like to read more click here.