iOS 9.3.5 (build 13G36) is an official Apple over-the-air update for the iPhone 4s, released on 2016-08-25T16:53:27Z. The update package is 51.72 MB. This is a delta (partial) update that requires 9.3 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 1ad8d17f2164a64188de9407e302fec841efc1fe.zip.