iOS 12.3 (build 16F5148a) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2019-04-29T17:36:07Z. The update package is 393.37 MB. This is a delta (partial) update that requires 12.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 8d237d60548cd58fb16a8cc8c1481db7964b3004.zip.