iOS 11.3 (build 15E5189f) is an official Apple over-the-air update for the iPhone 8 (GSM), released on 2018-02-20T18:06:23Z. The update package is 323.33 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: 342c0e387e1c532fbc699fb3082181446cdd107c.zip.