iOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPhone 8 (GSM), released on 2017-12-13T18:11:02Z. The update package is 393.53 MB. This is a delta (partial) update that requires 11.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b49c30f7cc63a42eb5ad051cf09f86527fbc646d.zip.