Apple has released iOS 18.3.1, along with a warning to update your iPhone now. That’s because iOS 18.3.1 is an emergency patch that fixes a single security issue that’s already being used in real-life attacks.
Apple doesn’t give much detail about what’s fixed in iOS 18.3.1, to give iPhone users as much time as possible to update before more attackers can get hold of the details.
But what we do know is, the iOS 18.3.1 update fixes a flaw in Accessibility where a physical attack may disable USB Restricted Mode on a locked device. “Apple is aware of a report that this issue may have been exploited in an extremely sophisticated attack against specific targeted individuals,” the iPhone maker said on its support page.
Tracked as CVE-2025-24200, the issue patched in iOS 18.3.1 was reported by Bill Marczak of The Citizen Lab at The University of Toronto’s Munk School.
iOS 18.3.1 — A Targeted Attack
As security researcher Josh Long writes, Apple’s USB Restricted Mode is a security feature added in iOS 11.4.1 included in all later versions of iOS and iPadOS. “USB Restricted Mode prevents locked devices from leaking data to any accessories connected to the USB-C or Lightning port,” Long says.
This means that for any accessory that does more than charging to work with your iPhone or iPad, the device needs to be unlocked at the time you connect it.
This helps prevent, for example, hacker tools such as Grayshift’s GreyKey from being able to break into a locked device, Long says. “Such hacker tools are mostly available to government and law enforcement agencies, but it’s possible for them to fall into the wrong hands.”
The nature of this attack is further backed up by the fact that the vulnerability was reported by The Citizen Lab — an organization that investigates digital espionage against civil society.
It was clear iOS 18.3.1 was coming — the update had been leaked last week, but no one knew what it contained. At the time, I speculated that it could include emergency security fixes, and it looks like I was right. Apple only released iOS 18.3 at the end of Jan., again illustrating the emergency nature of this iPhone upgrade.
Why You Should Update Now to iOS 18.3.1
The attack fixed in iOS 18.3.1 was highly-targeted, probably affecting high-profile people such as journalists, dissidents, some businesses and government officials. If you fit into this group, update right now.
Apple’s iOS 18.3.1 is available for the iPhone XS and later, iPad Pro 13-inch, iPad Pro 12.9-inch 3rd generation and later, iPad Pro 11-inch 1st generation and later, iPad Air 3rd generation and later, iPad 7th generation and later, and iPad mini 5th generation and later. If you have one of these devices, you should update now to protect your iPhone or iPad from attacks.
Apple issued iOS 18.3.1 alongside iPadOS 17.7.5, but this is only available for the iPad Pro 12.9-inch 2nd generation, iPad Pro 10.5-inch, and iPad 6th generation. There is no iPhone update for older iPhones which could be because they are not impacted, but as far as I am aware, Apple is not updating iOS 17 for this who simply want to choose to stay on the older operating system.
With the flaw fixed in iOS 18.3.1 being used in real-life attacks, it’s essential that you update your iPhone now to keep it safe. You know what to do. Go to your Settings > Software Update and upgrade your iPhone to iOS 18.3.1.