iOS 9.3.6 (build 13G37) is an official Apple over-the-air update for the iPhone 4s, released on 2019-07-22T17:06:50Z. The update package is 932.71 MB. This is a delta (partial) update that requires 8.0.1 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: f82fa2f9dcecbec878767080f0d77eade23d3c7d.zip.