CVE Numbers: CVE-2015-8562
A recently discovered zero day vulnerability within Joomla is currently being actively exploited, this vulnerability allows an attacker to take full control of an affected site’s administration area.
This exploit affects versions 1.5 through 3.4.5, you can determine your Joomla version by logging into your administrator area, your version will displayed either in the top right hand corner or at the bottom of your administrator panel.
If your site is an affected version it is essential you either upgrade or apply the latest patches.
If you are running any currently supported version of Joomla you should upgrade to the latest version
For EOL versions a patch has been provided which can be found at the link below, however we strongly recommend client’s upgrade to the latest version as soon as possible.