WhatsApp has recently fixed a bug that actually allowed hackers to crash the App during calls. Both Android and iOS devices were affected by this bug however the company now seems to have resolved the issue.
This bug was first discovered by a security researcher and was reported to WhatsApp in the month of August. The users were at increased risk especially during video calls on the app.
However WhatsApp for WebRTC was unaffected since the WebRTC is used for video conferencing. The bug got however fixed on the 28th of September. WhatApp has also recommended users to update their app to the latest version on Android and iOS.