https://www.cnet.com/news/fortnite-had-a-security-vulnerability-that-let-hackers-take-over-accounts/

The researchers discovered the vulnerabilities in November, and it was fixed by January. "We were made aware of the vulnerabilities and they were soon addressed. We thank Check Point for bringing this to our attention. As always, we encourage players to protect their accounts by not reusing passwords and using strong passwords, and not sharing account information with others," an Epic Games spokesperson said. 

Fortnite had a breakthrough year in 2018, with nearly 80 million players. Its parent company, Epic Games, was estimated to profit $3 billion last year, and valued at more than $15 billion for the free game. With the game's massive popularity comes security concerns.