iOS 12.1.1 (build 16C50) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2018-12-05T18:10:17Z. The update package is 1.35 GB. This is a delta (partial) update that requires 11.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: fb9068c6ef53b2d853cb6efdf7e8d70b8d96910d.zip.