WhatsApp has been found vulnerable to multiple security flaws that could allow malicious users to spread fake news through group chats. The flaws take advantage of a bug in the security protocols to modify the messages. An attacker could exploit the flaws to intercept and manipulate messages sent by those in a group or private conversation as well as create and spread misinformation The issues affect the way WhatsApp mobile application communicates with the WhatsApp Web and decrypts the messages using the protobuf2 protocol.”]
Source: https://securityaffairs.co/wordpress/75191/hacking/whatsapp-flaws.html