"The issue affects WhatsApp for Android prior to v2.19.134, WhatsApp Business for Android prior to v2.19.44, WhatsApp for iOS prior to v2.19.51, WhatsApp Business for iOS prior to v2.19.51, WhatsApp for Windows Phone prior to v2.18.348, and WhatsApp for Tizen prior to v2.18.15," Facebook says.

Whatsapp has recently patched a severe vulnerability that was being exploited by attackers to remotely install surveillance malware on a few "selected" smartphones by simply calling the targeted phone numbers over Whatsapp audio call.Discovered, weaponized and then sold by the Israeli company NSO Group that produces the most advanced mobile spyware on the planet, the WhatsApp exploit installson to Android and iOS devices.According to an advisory published by Facebook, a buffer overflow vulnerability in WhatsApp VOIP stack allows remote attackers to execute arbitrary code on target phones by sending a specially crafted series of SRTCP packets.Apparently, the vulnerability, identified as, can successfully be exploited to install the spyware and steal data from a targeted Android phone or iPhone by merely placing a WhatsApp call, even when the call is not answered.Also, the victim would not be able to find out about the intrusion afterward as the spyware erases the incoming call information from the logs to operate stealthily.Though the exact number of targeted WhatsApp users is not yet known, WhatsApp engineers did confirm that only a "select number" of users were targeted by the NSO Group spyware using this vulnerability.Meanwhile, Citizen Lab, a watchdog group at the University of Toronto which is investigating NSO Group's activities, believe the vulnerability was used to attack a UK-based human rights lawyer as recently as Sunday.NSO Group's Pegasus spyware allows attackers to access an incredible amount of data from victims' smartphones remotely, including their text messages, emails, WhatsApp messages, contact details, calls record, location, microphone, and camera—all without the victims' knowledge.The nasty spyware has previously been used against human rights activists and journalists , from Mexico to the United Arab Emirates , and Amnesty International staffers in Saudi Arabia and another Saudi human rights defender based abroad earlier last year.The vulnerability affects all except the latest version of WhatsApp on iOS and Android, meaning the flaw affected all 1.5 billion people using WhatsApp until yesterday when Facebook finally patched the issue.WhatsApp engineers discovered the vulnerability earlier this month and alerted the Department of Justice of the issue. They encourage users on both iOS and Android to update their apps to the latest version of the popular messaging app as soon as possible.