One week ago a security firm and University of  Toronto’s Citizen Lab detected a serious security flaw of iOS. For this security flaw it'll be possible to hack  the iPhones of famous personalities, journalists, and activists.  

However Apple released an update of iOS devices including iPhones, iPods, OS X & Safari browser to fix this security flaw.

Urgent !!! Please, update immediately your mac devices from App Store !!!

Source of the news : https://www.hackread.com/apple-mac-os-x-safari-security-flaw-update/