Software components on the server should be updated periodically, as security issues in old versions are discovered. Most important is PHP and its supporting libraries. Version 5.2 is officially unsupported since 2011 and 5.3 since 2014 (see the actual PHP support schedule here). Security issues will not get fixed for expired versions, so running an old PHP version implies high risk of a security breach of your shop.
How do I fix it?
If you have checked your site using MageReport.com and you host your site at Byte, the scan will indicate that the server has been maintained and, therefore, is up-to-date. Because at Byte, you benefit from managed hosting. This means we ensure that the server(s) on which your site or shop runs is always up-to-date and, therefore, secure.
Unfortunately, we do not have full insight into the web servers of other hosters and this means that we cannot indicate which software updates you must implement. Do you not host at Byte? Please contact your webhoster to find out how well the servers on which your shop runs are maintained.
Do you have your own server on which Magento runs? Check which software you use and have installed on your server(s) and check for updates. Before you update software, always check the release notes (if available). By doing so, you can check whether specific components might conflict with other software.
If you feel you are missing skills or time to properly secure your Magento shop, we can recommend hiring one of these agencies.