An obsolete version of any program can make your Joomla website security vulnerable. It is important to check if you are running a secure version of PHP. You can check your version of PHP from “System Information” in the System menu. Official support for the PHP version till 5.6.0 is ended officially.
So, if you find your PHP version is less than 5.6.0, we recommend that you submit a support ticket to your host provider and request a secure PHP version. The latest version of PHP comes with previous Joomla website security fixes, so it is always advised to use the most recent version of PHP.