iOS 18 holdouts: 18.7.7 is out now for devices that were eligible for the 26 upgrade. You should upgrade immediately. The security updates are significant. https://www.macrumors.com/2026/04/01/apple-ios-18-darksword-security-update/
Apple Issues Rare iOS 18 Security Update to Protect Against DarkSword Exploit

Apple today released a new build of iOS 18.7.7 and iPadOS 18.7.7, presumably with a fix for the DarkSword exploit. Apple told Wired that it would...

MacRumors
If you’ve turned on iOS 18 beta updates to avoid getting nagged about iOS 26, this update won’t show up. I had to turn off beta updates for it to show up.