Largest WhatsApp Data Leak in History Exposes 3.5bn Users

Researchers in Austria say they have uncovered what could be the largest data leak in history after exploiting a flaw in messaging platform WhatsApp to collect personal details of more than 3.5 billion users.The team found that WhatsApp’s longstanding feature allowing users to look up accounts by entering phone numbers can be abused to “enumerate” massive amounts of user data — including phone numbers, names, and in many cases profile photos.Using a tool built with technology from libphonenumber, the researchers generated 63 billion phone numbers and queried them at a rate of over 100 million accounts per hour. They said WhatsApp imposed no effective rate-limiting, allowing them to confirm 3.5 billion registered numbers — far higher than the “more than 2 billion” figure previously cited by the platform.According to their report, 57 percent of active accounts examined had a profile photo, two-thirds of which showed identifiable human faces. Another 29 ...

• 24 Nov 2025