情報來源：
https://i.imgur.com/Ws70rm5.jpg
死守 iOS 12 跟被蘋果放生的機型可以更新，
據聞只是安全性修正。
iOS 12.4.2
Released September 19, 2019
Foundation
Available for: iPhone 5s, iPhone 6, iPhone 6 Plus, iPad Air, iPad mini 2, iPad mini 3, and iPad touch 6th generation
Impact: A remote attacker may be able to cause unexpected application termination or arbitrary code execution
Description: An out-of-bounds read was addressed with improved input validation.
CVE-2019-8641: Samuel Groß and Natalie Silvanovich of Google Project Zero
https://support.apple.com/en-us/HT210590