iOS 12.3 (build 16F5139e) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2019-04-22T17:08:55Z. The update package is 392.28 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: 27eb6ee49cb044ac808bf9311e4376cc37e3c82f.zip.