Download iOS 15.3 (19D50) IPSW for iPhone 6s
This firmware is signed. This means that you can restore to it in iTunes.
iOS 15.3 Release Notes
Please note, the documentation below is supplied from Apple’s update servers. We don’t modify the contents of this documentation.
iOS 15.3 includes bug fixes and security updates for your iPhone and is recommended for all users.
For information on the security content of Apple software updates, please visit this website: