Kirby is a CMS. In Kirby CMS (getkirby/cms) before version 3.3.6, and Kirby Panel before version 2.5.14 there is a vulnerability in which the admin panel may be accessed if hosted on a .dev domain. In order to protect new installations on public servers that don't have an admin account for the Panel yet, we block account registration there by default. This is a security feature, which we implemented years ago in Kirby 2. It helps to avoid that you forget registering your first admin account on a public server. In this case – without our security block – someone else might theoretically be able to find your site, find out it's running on Kirby, find the Panel and then register the account first. It's an unlikely situation, but it's still a certain risk. To be able to register the first Panel account on a public server, you have to enforce the installer via a config setting. This helps to push all users to the best practice of registering your first Panel account on your local machin

Kirby .dev domains and some reverse proxy setups were treated as local