iOS 8.4.1 (build 12H321) is an official Apple over-the-air update for the iPhone 5 (GSM), released on 2015-08-13T18:05:13Z. The update package is 407.8 MB. This is a delta (partial) update that requires 8.1.2 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 08b93594409f8245006f96519b39ec411a20b38f.zip.