WhatsApp has urged its users (and there are 1.5 billion of them worldwide) to update their app immediately after cyberattackers used a vulnerability in the platform to inject commercial Israeli spyware on to phones. The spyware, Pegasus, is intended for governments to fight terrorism and crime, but there is evidence that it’s been used by governments to spy on its own citizens. The World’s host Marco Werman talks to a cybersecurity expert about exactly what happened and its implications. Werman also speaks with Isabelle Santos, a 24-year-old in Rio de Janeiro, who explains the role the messaging app WhatsApp plays in her life.