iOS 9.3.6 (build 13G37) is an official Apple over-the-air update for the iPhone 4s, released on 2019-07-22T17:06:59Z. The update package is 18.31 MB. This is a delta (partial) update that requires 9.3.5 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: df2745322c9dcb2f328c76cc9c4c0aef5afe018c.zip.