Billions of iPhone users and Apple device owners worldwide are being warned to update their devices immediately after a major security flaw puts them at risk of malware attacks.

What’s being called “AirBorne” allows hackers to deploy malware, snoop on your private data, or even eavesdrop on your conversations when connected to the same WiFi network as your devices, which includes public places like airports, coffee shops, or even your work office.

These attacks usually target journalists, activists, politicians, and diplomats. Apple has sent alerts to iPhone users in 100 countries and recommends they enable Lockdown Mode.