Tool allows stealthy tracking of Signal and WhatsApp users through delivery receipts

Pogowasright •Dissent • December 12, 2025

Alex Lekander reports: A new tool named Device Activity Tracker exposes a persistent privacy flaw in WhatsApp and Signal that lets attackers covertly monitor user activity using only their phone number. Based on academic research from the University of Vienna and SBA Research, the tool demonstrates how delivery receipts, normally a harmless feature, can be weaponized...

The full story

This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Privacy Flaw in Signal and WhatsApp Allows User Tracking via Delivery Receipts A new tool named Device Activity Tracker exposes a privacy flaw in WhatsApp and Signal, enabling attackers to monitor user activity using only their phone number. This vulnerability leverages delivery receipts, which are typically benign, to covertly track users. The research originates from the University of Vienna and SBA Research. 2 sources 24

Tool allows stealthy tracking of Signal and WhatsApp users through delivery receipts

The full story

Extracted Entities

Companies (1)

Platforms (1)

Tools (1)