An Israeli firm has a found a security hole in the app, WhatsApp, using it to break into iPhone and Android phones - the same firm that has also been accused of supplying tools for spying on human-rights activists and journalists.
WhatsApp engineers have been working tirelessly to fix the issue and released a new app update on Monday that fixes the vulnerability.
The company said in a statement they encourage people to upgrade to the latest version of the app, as well as keep their mobile operating system up to date, to protect against potential targeted exploits designed to compromise information stored on mobile devices."