People often get all freaked out when they hear about security flaws in content management systems like Joomla. This is the nature of the beast. You shouldn't be worried if your CMS-based website has security holes as much as if the developers are fixing them quickly. In this case, it was fixed on the same day it was reported.
If you are running a Joomla site, I've posted the alert details here.
Likely you're not running a Joomla website, maybe you run Wordpress or something custom, this is still an opportunity for me to remind you that ALL database driven software can have security issues.
If you've not had your site updated recently, AND if you have data you care about, have your tech make sure you're current. Upgrading is fast, inexpensive and far less painful than when someone emails you with,
"Hey, looks like your site has been hacked/hijacked."