It's a pretty common setup on servers, even if it's not the majority. Probably more commonly it's part of the boot sequence on servers even if it's not used. I would say this is a relevant issue for most organizations' network security because of the risk it represents of being able to escalate from compromising a less privileged machine (e.g. a user's device) to a more privileged machine. It's not a 'oh god every server is going to be pwned' issue, but it doesn't need to be to be worth alerting people to.

Several large bare-metal hosting companies. Not over the open Internet, but that doesn't matter if the management networks are shared and the price of admission a single server rental.

> No, I don't think network booting is even all that common outside of extremely niche scenarios.

It's incredibly common though? I've run across it and I work on games and client software, not server stuff.

> Another breathless fearmongering.

It's Ars; you come to expect it.