Apple has released iOS 26.3.1(a), bringing the companies first Background Security Improvements update, a smaller, security-focused update that sits in a different place in the iPhone and handles urgent issues.
There’s another difference, too, from a regular update: it’s easily uninstalled.
Like other iOS 26 updates, this one is supported by all iPhones from 2019 on, so if you have an iPhone 11 or later, then it’s for you.
Once installed, next to the update, in the same place, is an “i” in a circle. That’s what you tap to uninstall the update if you’ve been having problems – a feature standard iPhone updates don’t offer.
iOS 26.3.1(a) is about an issue in WebKit, called CVE-2026-20643. It could potentially allow bad actors to access data from other open tabs in the iPhone’s browser.
iOS 26.3.1(a) Security Updates
WebKit
Available for: iOS 26.3.1, iPadOS 26.3.1, macOS 26.3.1, macOS 26.3.2
Impact: Processing maliciously crafted web content may bypass Same Origin Policy
Description: A cross-origin issue in the Navigation API was addressed with improved input validation.
iOS 26.3.1(a) Supported Devices
- iPhone 17
- iPhone 17 Pro
- iPhone 17 Pro Max
- iPhone Air
- iPhone 16
- iPhone 16 Plus
- iPhone 16 Pro
- iPhone 16 Pro Max
- iPhone 15
- iPhone 15 Plus
- iPhone 15 Pro
- iPhone 15 Pro Max
- iPhone 14
- iPhone 14 Plus
- iPhone 14 Pro
- iPhone 14 Pro Max
- iPhone 13
- iPhone 13 mini
- iPhone 13 Pro
- iPhone 13 Pro Max
- iPhone 12
- iPhone 12 mini
- iPhone 12 Pro
- iPhone 12 Pro Max
- iPhone 11
- iPhone 11 Pro
- iPhone 11 Pro Max
To update to iOS 26.3.1(a) go to your iPhone Settings > Privacy & Security -> Background Security Improvements.
Background Security Improvements
Background Security Improvements deliver additional security protections between software updates.
Background Security Improvements deliver lightweight security releases for components such as the Safari browser, WebKit framework stack and other system libraries that benefit from smaller, ongoing security patches between software updates.
In rare instances of compatibility issues, Background Security Improvements may be temporarily removed and then enhanced in a subsequent software update.
Background Security Improvements are supported and enabled for future releases starting with iOS 26.1, iPadOS 26.1 and macOS 26.1.
View Background Security Improvements in Settings
Settings for Background Security Improvements can be found in the Privacy and Security menu.
- On iPhone and iPad: go to Settings, then tap Privacy & Security.
- On Mac: from Apple menu, choose System Settings. Then click Privacy & Security.
Go to Background Security Improvements and make sure “Automatically Install” is turned on.
If you choose to turn off this setting, your device will not receive these improvements until they’re included in a subsequent software update.
If a Background Security Improvement has been applied, and you choose to remove it, your device will revert to the baseline software update with no Background Security Improvements applied.
