Here’s a draft piece on — written as an explanatory / technical overview for a blog or knowledge base. checkm8-a5: The Bootrom Exploit That Changed A5 Devices Forever Introduction In the world of iOS jailbreaking and security research, few exploits carry the weight of checkm8 . Released in September 2019 by axi0mX, checkm8 was the first permanent, unpatchable bootrom exploit for hundreds of millions of iOS devices. Among the affected chips was the Apple A5 — used in the iPhone 4S, iPad 2, iPad mini (1st gen), and iPod touch (5th gen).