Two India based independent security researchers, Indrajeet Bhuyan and Saurav Kar, both 17-year old teenagers demonstrated the WhatsApp Message Handler vulnerability to one of our security analyst. The worried impact of the vulnerability is that the user who received the specially crafted message will have to delete his/her whole conversation and start a fresh chat, because opening the message keeps on crashing WhatsApp unless the chat is deleted completely. The vulnerability has not been tested on iOS, but it is sure that all versions of WhatsApp including 211.431 and 2.11.432 are affected.
Source: https://thehackernews.com/2014/12/crash-your-friends-whatsapp-remotely_1.html