Googles project zero researchers Natalie Silvanovich found a vulnerability that allows an attacker to compromise your device just by answering a video call on the app.
The problem was a memory heap overflow issue, triggered when a user received a corrupted RTP header via the video call request. This corruption can be smartly manipulated to cause your phone to immediately crash or in worst case scenario the compromise of your device.
A proof of concept for this vulnerability was published by Silvanovich that uses this vulnerability to cause memory corruption in both android and IOS devices
In other words, it means that the attackers only requires your phone number to hijack your account.
On September 28 and October the 3rd, WhatsApp patched this vulnerability in android and IOS respectively. So if you havent updated WhatsApp yet, we highly suggest you do it now.