For all of its end - to - end encryption , hackers have found a way in , compromising a very small percentage of the App 's estimated 100 m active users . The vulnerability was exploited on the web version of WhatsApp , with hackers sending random phone numbers with malware loaded vCards . WhatsApp recently announced it had reached 900 million active users with around 200 million estimated to be using the web-based version. Once the vCard was ' accepted ' by a web - based version of the app , the malware was downloaded and phone numbers and IDs sent back to the user . WhatsApp were told of the vulnerability in late August and had it patched up later .
For all of its end - to - end encryption , hackers have found a way in , compromising a very small percentage of the App 's estimated 100 m active users . The vulnerability was exploited on the web version of WhatsApp , with hackers sending random phone numbers with malware loaded vCards . Once the vCard was ' accepted ' by a web - based version of the app , the malware was downloaded and phone numbers and IDs sent back to the user . WhatsApp were told of the vulnerability in late August and had it patched up later .