From time to time, patches are released as flaws are noted and / or companies such as PayPal, Authorize.net, etc. make changes to their protocol. It is VERY IMPORTANT that you, as a business owner using the Zen Cart software, stay on top of any fixes that come out.
One way to stay informed is to make sure you are signed up for our newsletter. We attempt to let people know of any fixes that come out.
Keep in mind that having your Zen Cart website upgraded to the current version is the very best way to make sure your website is secure!