SUPEE-5994 is the patch you need to install on your Magento stores (Enterprise and Community). It’s a little to late to prevent you, but i saw a lots of visitors searching for this patch on my website, so I decided to post it now.
SUPEE-5994 is a complementary patch of the one published on february, le SUPEE-5344.
Install the 5344 if you didn’t do it before the 5994.
This is a critical RCE (remote control execution) vulnerability, that allows attackers to access all the data in your online store.
Patch for Magento Community : https://www.magentocommerce.com/products/downloads/magento/
Find the patch with his name, they are at the bottom of the page in “Magento Community Edition Patches” rubric.
Patch for Magento Enterprise, you need to log on the portal : https://www.magentocommerce.com/products/customer/account/login/