Facetime being popular and having a bug that gives someone complete access to info on your phone can be an extremely risky bug to have. The new bug gives someone the ability to steal contact info off your phone through a facetime call.
“A bad actor would need physical access to the phone that they are targeting and has a few options for viewing the victim’s contact information. They would need to either call the phone from another iPhone or have the phone call itself. Once the call connects they would need to:”
source:
https://www.schneier.com/blog/archives/2018/11/ios_121_vulnera.html
Blakes Cyber Security Blog 