iOS 11.3 (build 15E5189f) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2018-02-20T18:06:24Z. The update package is 296.93 MB. This is a delta (partial) update that requires 11.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 4829b051e41c135fcf1737723eeea2be28aa096a.zip.