WhatsApp group chat flaw can wreak havoc on users of older app versions
While said bug fix discreetly rolled out to the masses in mid-September as part of an update to app version number 2.19.58, many WhatsApp users could still be vulnerable to a sneak group chat attack by a "bad actor" looking to prevent you from opening the IM app for some reason. In order to avoid that, you simply need to make sure you have the latest version of WhatsApp installed on your Android handset or iPhone.
Otherwise, all someone has to do to render the app unusable for you is create an innocent-looking message with certain specific parameters edited in a debugging tool and send the malicious text to a group including the bad actor as a member to begin with. That last part may sound a little tricky, but with up to 256 users allowed to join any specific WhatsApp group, it's often hard to keep track of the identity and intentions of every single member in every single group chat.
Once the malicious message hits the target group, there's nothing left to do for victims of this incredibly efficient attack but uninstall and reinstall WhatsApp to regain access to the app, and perhaps worst of all, delete the group containing the mischievous text. Once again, all you have to do to dodge this scary threat is keep the app up to date, which you should really do even in the absence of revelations like these as smaller but sometimes similarly important security enhancements are frequently applied in new WhatsApp versions.