Apple is advising users to immediately update software due to a vulnerability that may have already been discovered by hackers.

CNN reported Apple has issued an update to iOS 16.1.1. According to Apple, the update applies to iPhone 8 and later, all models of the iPad Pro, iPad Air 3rd generation and later, iPad 5th generation and later, and iPad mini 5th generation and later.

As reported by Bloomberg, The Citizen Lab at the University of Toronto discovered an iPhone belonging to a staffer at a Washington-based civil society organization was hacked remotely by spyware traced to Israel’s NSO Group.

“Citizen Lab found an actively exploited zero-click vulnerability being used to deliver NSO Group’s Pegasus mercenary spyware while checking the device of an individual employed by a Washington DC-based civil society organization with international offices,” The Citizen Lab said in its statement.

iPhone and iPad owners are advised to immediately go to their device’s settings menu, select general and then software update. Tap install to start the update process.