iOS 12.1.3 (build 16D5039a) is an official Apple over-the-air update for the iPhone 8 (GSM), released on 2019-01-10T18:08:56Z. The update package is 293.54 MB. This is a delta (partial) update that requires 12.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 17240735e5b2a097bb636bcaf05ce4f9daa2f4aa.zip.