iOS 9.3.6 (build 13G37) is an official Apple over-the-air update for the iPhone 4s, released on 2019-07-22T17:06:57Z. The update package is 35.73 MB. This is a delta (partial) update that requires 9.3.2 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 7aa0e7e4142ed2d40afe50bb19af893f711aee09.zip.