Millions of Fornite gamers may have allowed hackers to download malicious apps onto their phones without ever realising.
A serious flaw in the first Fortnite installer - an app that helps users download the game on their Android phones - allowed any app on a user's phone to silently install other apps.
The discovery was made by Google's security team after Fornite maker, Epic Games, decided to release its own installer as a way to bypass the Google Play Store.
The Google Play Store is the app store for Android phones, used on smartphone models from Samsung, Sony and Huawei.
It is considered a more secure way to download apps from the internet, which could contain viruses or malware.