iOS 12.1.3 (build 16D5032a) is an official Apple over-the-air update for the iPhone 8 (GSM), released on 2018-12-19T18:06:55Z. The update package is 332.8 MB. This is a delta (partial) update that requires 12.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 59c94de7bd4abea0f60921e6fc454a998d6f06ed.zip.