iOS 12.1.3 (build 16D5039a) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2019-01-10T18:09:05Z. The update package is 225.43 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: a4f8290069019b7f493ae31ee77993401f9cf4d5.zip.