Facebook Messenger had a bug that allowed hackers to listen in on users phone calls. This bug has now been fixed. A month ago, the bug was found by Natalie Silvanovich from the Google Project Zero, and it had supposedly only had an effect on Android users Messenger, while iOS users were safe.
When the bug was vulnerable, hackers were able to start a call by sending a specific ‘invisible’ message, which allowed them to listen in to the user’s call.
If both, the hacker and the victim were logged on to Messenger, and the victim had been logged in Messenger through their browser, then only was the hacker capable of going through with the hack. Otherwise, only people on the users’ friend lists would’ve been able to hack into a call.
In apps such as Signal, Mocha, and JioChat, many similar bugs had been found by Silvanovich, which have all been fixed now.