iPhones can be taken over at will by hackers if they are not updated to iOS 10.3.3

All a phone needs to do is be in range of a WiFi network and attackers can make their way in

A customer compares pictures taken with an Iphone 6 (R) and the new Iphone 7 (L) at Puerta del Sol Apple Store the day the company launches their Iphone 7 and 7 Plus on September 16, 2016 in Madrid, Spain (Gonzalo Arroyo Moreno/Getty Images)

iPhones that aren't updated to the latest version of iOS could be taken over by hackers at will.

All that's needed to break into a phone is for it to be near a corrupted WiFi network, experts have warned. The phone doesn't even need to connect to the network to be attacked.

But thankfully the problem can be fixed with a simple update.

iOS 10.3.3 – the latest version of the software – patches up the problem so that hackers won't be able to get into phones. But until they are updated all recent iOS devices are vulnerable.

The release notes on Apple's website say that the exploit could hit the iPhone 5 or later, everything since the fourth generation of the iPad and the newest iPod Touch. They also say that "attacker within range may be able to execute arbitrary code on the Wi-Fi chip".

Apple said that iOS 10.3.3 includes bug fixes, but it's not clear whether it addresses any other problems. It doesn't add any new user-facing features.

It's still not clear how the exploit works, apart from the fact that it takes over the Broadcom chip that powers the WiFi in an iPhone. The security researcher who found it, Nitay Artenstein, will give details on it at a security conference later this month.

The same problem chip is used in other Android phones, according to security experts. Google has already fixed that in the latest version of the operating system, but since manufacturers are often delayed in getting updates out to different phones it may not have arrived on specific models yet.