iOS 13.3.1 (build 17D5026c) is an official Apple over-the-air update for the iPhone X (GSM), released on 2019-12-17T18:13:26Z. The update package is 247.76 MB. This is a delta (partial) update that requires 13.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 7b18f4f5cce3ae7e9104abec0278c89d988d3864.zip.