Basically all the hacker has to do is to trick users into opening a JPEG file or even a PDF that can come either as an email attachment or from a website. Once the file has been open, the hacker will then be able to execute malicious code on your device that would grant them access to it and take full control, meaning that your files and information stored on your device would be an open book.
Before you panic and decide never to visit another website or open a PDF ever again on your iPhone or iPad, not to worry because The Hacker News claims that this flaw was fixed by Apple in the latest iOS 10.1 update which was released yesterday. The update to iOS introduces Portrait Mode for the iPhone 7 Plus and also patches this flaw amongst other security flaws that were discovered, as well as introduce a host of bug fixes, so if you haven’t done so already, you should definitely update to iOS 10.1 ASAP.