Whatsapp servers can be compromised to add people to private groups - engadget
Hey, there is a segnificant security flaw in whats app again...
... Anyone in control of a Whatsapp server can add people to a private group with minimal effort.
For more information here the original story.
https://www.engadget.com/2018/01/10/whatsapp-add-people-to-private-groups-security-flaw/