Which organisational problems add to the risk of publisher Z's LAMP platform?

Poor maintenance with missing updates; the know-how lies with the external provider who built it, so there is no internal knowledge and there are no internal developers; and development and production are possibly not separated.

These problems explain why the technical ones exist and why they persist. The platform was built years ago by an external service provider, apparently without a maintenance arrangement, so nobody at Z can fix the input validation or upgrade PHP, and nobody is tasked with doing so. If development and production are not separated, changes are tested on the live system (or not tested at all), and development tools, test accounts and debug settings end up exposed on the internet. Any new architecture therefore has to fix the organisation as well, through processes for patching and updates and a maintenance contract with a developer.

Go deeper:

• Deployment environment — Wikipedia — why development, test and production are kept apart.
• NIST SP 800-40 Rev. 4 — Guide to Enterprise Patch Management Planning — treating patching as planned, preventive maintenance.