iOS 12.1.3 (build 16D39) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2019-01-22T18:09:34Z. The update package is 1.32 GB. This is a delta (partial) update that requires 11.2.5 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: af42782ac3f9a3c74eaba79b9a385bca8f9e70af.zip.