GoKawiilApple released iOS 26.3.1 (a), its first Background Security Improvement, on Tuesday, March 17. The tech giant wrote online that the update fixes an issue in WebKit, the engine that powers Safari and other third-party browsers in iOS.
If you have enabled automatic installation of Background Security Improvements, your iPhone should install this update on its own. If you don't have automatic installs, or if you want to make sure your iPhone downloaded the update, go to Settings > Privacy & Security > Background Security Improvements. From here your iPhone will either say iOS 26.3.1 (a) is already installed or you'll see an option to install the update.
Apple/CNET
Apple usually notes when an update addresses a bug that has been exploited in the wild. While the company didn't indicate whether that's the case for this update, Apple recommends everyone download the update.
Apple introduced Background Security Improvements in November when the company released iOS 26.1. "Background Security Improvements deliver lightweight security releases for components such as the Safari browser, WebKit framework stack, and other system libraries," Apple wrote online.
These new updates remind me of the Rapid Security Responses that Apple introduced in 2023. Those updates were a way for the company to quickly deploy security fixes to devices, similar to the Background Security Improvements, and both updates share the same naming convention. However, Apple hasn't issued a Rapid Security Response since the release of iOS 16.5.1 (c) in July 2023.
Apple did not immediately respond to a request to comment on any relationship between Rapid Security Responses and Background Security Improvements. For more iOS news, check out what to know about iOS 26.3.1 and iOS 26.3. You can also take a look at our iOS 26 cheat sheet for other tips and tricks.