A new version of Joomla has been released and it's an important security release. There was a High Priority Remote Code Execution (affecting Joomla 1.5 through 3.4.5). Evidently your site can be very easily hacked if you are not running the latest Joomla version 3.4.6.
This vulnerability affects all versions of Joomla including Joomla 1.5 and 2.5 versions. Since these versions of Joomla are no longer supported, there will be no patches released. It is strongly advised that you migrate to Joomla 3.x as soon as possible if you are using an outdated version of Joomla.
Be advised - if your website is compromised, your website host may shut down your website until you can get it fixed or get someone to fix it for you. That could take days or even weeks or more. If your website is an important part of your business (and it should be), then make sure you take care of it.
Joomla! 3.4.6 Released (joomla.org)
Joomla! 3.4.6 is now available. This is a security release for the 3.x series of Joomla which addresses a critical security vulnerability and 2 low level security vulnerabilities. We strongly recommend that you update your sites immediately.
This release only contains the security fixes; no other changes have been made compared to the Joomla 3.4.5 release.
We highly suggest performing this upgrade since this is a security release.
Our Website Maintenance Department will be in contact with all of our clients running Joomla regarding these upgrades.