iOS 12.1.3 (build 16D39) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2019-01-22T18:09:26Z. The update package is 1.7 GB. This is a delta (partial) update that requires 10.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 41e9ba56648c6d6f912891257f33d3fa8ad65af4.zip.