It’s been two years since WhatsApp added end-to-end encryption in all their conversations. Although this increases the security and privacy of our chats, a security error has been discovered that allows access to private groups by skipping encryption.
German cryptographers discover a security error in WhatsApp
The main factor that leads to establishing a point-to-point encryption answers the question of privacy: messages should only be read by the sender and the recipient. The moment the message arrives or passes through another person or server, the filtering has failed. And this is what a team of German cryptographers has discovered during a security conference in Switzerland.
Source-https://techviral.net/hackers-secretly-add-members-whatsapp-group/