ucms.php is designed to be used on a local system, behind any local firewall and preferably on a virtual machine or a machine set aside for local content management.
Because of this, there is no code within the system to restrict access. If you require a system to use on a web server that also serves pages to the external internet (even if you host your own pages on a local dmz), you must use a system designed for this with the necessary security designed in from the start.
One of the main benefits of the ucms.php system is that being a local system that does not serve its pages to an external audience, you can modify both the pages and the ucms.php system without fear of breaking the live web site or introducing some security exploit.
Naturally, because of this, ucms.php is only suitable for websites that do not need to be managed remotely.
As the system can be used inside a virtual machine and the supporting software quite small, it is possible to backup the whole system onto a memory stick or dvd and load that backup onto another machine.
As the system was being built, one of the design goals was that the system should be able to be used by a designer or developer to create a website and then be able to deliver the entire thing (pages, templates and system) to a customer who could then manage the site in-house.