In October 2026, a major issue occurred due to a vulnerability in the PHP programming language. At that time, various services were forced to temporarily shut down, but there was no direct solution for the PCs and smartphones we use. Why was that the case? To understand this, let's take a look at how the Internet works.
One of the basic mechanisms of communication on the Internet is called the "client-server" model. A client usually refers to our PCs or smartphones. The client sends requests to another computer called a server. The server then responds to these requests by sending back data.
A server is typically a computer located in a physically separate place with a different role, like a large desktop PC without a display. It supports the services we use behind the scenes.
When security issues with PHP arise, it is the server side that needs to be addressed. This is because PHP runs on the server's computer. Let's look at a more concrete example.
Consider the case when we display a website from a web browser on our PC or smartphone. When we enter the URL of the site into the web browser, a request is sent to the server. This is called "sending a request." When the server receives the request, it prepares the data and formats it so that it can be displayed. PHP mainly plays a role in this part. After that, the data is returned to the client and displayed in our web browser.
The basic mechanism is the same when using a service from an app on a smartphone or PC. The client app sends a request to the server, and the server responds with the requested data. At this time, server-side programs such as PHP prepare and process the data before returning it to the client.