Apple today released the first Background Security Improvement (BSI) update, replacing the rapid security updates that it used to seed out a few years ago. The first BSI updates address a WebKit vulnerability that could allow maliciously crafted web content to bypass Same Origin Policy. There's a macOS Tahoe 26.3.1, iOS 26.3.1, and iPadOS 26.3.1 BSI update, as well as a macOS Tahoe 26.3.2 BSI update exclusive to the MacBook Neo.
Apple says that the vulnerability was addressed with improved input validation.
Background Security Improvements were added with iOS 26, iPadOS 26, and macOS Tahoe, and Apple tested them in iOS 26.3, iPadOS 26.3, and macOS Tahoe 26.3 before today's official release.
The updates are meant to provide additional security protections between software updates for Safari, WebKit, and other system libraries. Background Security Improvements can be installed in the Privacy and Security section of the Settings app. Scroll down, and then select the Install option to install the update. If Automatically Install is toggled on, BSIs will be automatically installed when they come out.
Users who opt not to install Background Security Improvements will receive the fixes in a subsequent standard software update.
Apple warns that Background Security Updates can result in "rare instances of compatibility issues." Should that occur, the updates may be temporarily removed and enhanced in another software update.
