iOS 12.3 (build 16F5148a) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2019-04-29T17:36:08Z. The update package is 88.63 MB. This is a delta (partial) update that requires 12.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 9af6c25c199474fc9e6c53d2f62f8a91c04f3fda.zip.