https://www.cnet.com/news/how-to-disable-apple-facetime-iphone-ipad-mac-bug/

You can read all about the bug here. 

Apple told CNET it's working on a fix for the bug which is due out in a software update "later this week." But considering this bug emerged on Monday, that might feel like a long time if you're security conscious. (Or, let's not lie, if your friends have just heard the news and are threatening to prank you every second of the day).