It's "critically important" that anyone with an Apple phone, tablet, computer or watch to update their device software as soon as possible, Newstalk's Jess Kelly says.
This applies to all of the company's devices - including iPhones, iPads, Apple Watches and MacBooks.
Yesterday, Apple released major security updates to cover all their main devices.
In their software release notes, the tech giant said they were addressing a vulnerability where a "maliciously crafted" PDF or web content could be used by hackers to access a device.
Crucially, the problem in question, which was identified by independent researchers in Canada, meant a device could be accessed without the user actually clicking on any document - a so-called 'zero-click exploit'.
Apple has said it's aware of a report the issue "may have been actively exploited".
On The Pat Kenny Show, Newstalk's technology correspondent Jess Kelly explained why this update is such a big deal.
— NewstalkFM (@NewstalkFM) September 14, 2021
She said: “If you have an Apple device... you need to update your software.
“This is an emergency software update that’s been pushed by Apple in the last day or so. It’s because a critical weakness within the infrastructure of the operating systems has been identified. Security researchers have found that if you don’t update your software, it could be vulnerable to Pegasus software.
“This is spyware that malicious actors could push onto your device without you knowing it. It’s called zero-click software.
"They can get access to your phone calls, your photographs... anything your device can do, essentially."
Jess urged people who have an Apple device to make sure they install the update that has now been pushed out by Apple.
She said: "The maximum it will take is ten minutes, but it is critically important that you do it.”
The exploit in question was identified by researchers at the University of Toronto's Citizen Lab.
They say they came across the issue while analysing the phone of a Saudi activist whose phone was infected with the Pegasus spyware.
Explaining their findings, researchers claim the Israeli "mercenary spyware company" NSO Group used the vulnerability in question "to remotely exploit and infect the latest Apple devices with the Pegasus spyware".
It's believed the exploit has been in use since at least February 2021.
The researchers reported the exploit to Apple earlier this month, leading to the software update that has now been pushed out to devices globally yesterday.