iOS 12.0 (build 16A366) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2018-09-12T19:10:33Z. The update package is 1.34 GB. This is a delta (partial) update that requires 11.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 1a60bd7cf3e86d872116b11bfc32fdfb505f2465.zip.