WhatsApp, metadata and privacy: when the problem is not the content but the context
In the final months of 2025 and early 2026, two independent studies highlighted significant vulnerabilities in WhatsApp’s metadata management. The University of Vienna and SBA Research demonstrated the ability to enumerate 3.5 billion accounts through the contact discovery mechanism, while Tal Be’ery (Zengo) showed how cryptographic key IDs allow inference of operating system, device type, and approximate session age. Meta has begun implementing fixes, but the privacy implications remain significant. This article analyzes the nature of metadata, WhatsApp-specific risks, and presents open source alternatives based on federated protocols such as XMPP and Matrix.
