A few days ago, Fortnite players discovered a glitch in the Fatal Fields area of the map that allowed them to slip under the game world and blast everyone else with impunity.
You can see it in action in the footage below captured by Spoderman Gg: players are able to disappear underneath the game map itself, and while down there can not only see everyone else in the game (who can't see them, since the ground is in the way), but shoot them as well.
It's quickly become known as the Fatal Fields Glitch, though there are reports of players being able to do it in Salty Springs as well.
As cool as it looks, and as easy as the kills are, it's also cheating. Before correcting the exploit, Epic warned players to report anyone they find taking advantage of Fortnite's great underworld:
We are aware of this exploit and working towards a fix. Until then please report any players you see abusing this. There are two ways of doing this. The first and most effective way is by opening a ticket here and providing any information you have.
The alternative way is by clicking the "Feedback" button and then using the "Player" tab to provide their username and what you're reporting them for. Players caught abusing this exploit will have action taken against their accounts.
They eventually fixed the exploit, and in terms of account action will be "looking at each case and our own analytics" before taking "appropriate action."
Success! The underground map exploit has been fixed and all wormholes leading to the underworld have been removed. For players who were reported, we are looking at each case and our own analytics and we’ll take appropriate action. Get out there and have some fun in the sun!
— Fortnite (@FortniteGame) January 15, 2018