WordPress 4.3.1 is now available and should be applied to all your sites as soon as possible as is a security release that addresses two cross-site scripting vulnerabilities and a potential privilege escalation. For more information, see the release notes or view the list of changes.

You can read more about the update: https://wordpress.org/news/2015/09/wordpress-4-3-1/

You can download WordPress 4.3.1: http://wordpress.org/wordpress-4.3.1.zip