A new BootROM exploit which is unpatchable potentially opens the door to jailbreaks, a researcher said. The exploit is dubbed checkm8 by a security researcher who goes by the alias axi0mX. Most generations of the iPhone and iPad are vulnerable: from iPhone 4S (A5 chip) to iPhone 8 and iPhone X (A11 chip) Most recent chip families, the A12 and A13, are impacted. Apple did not respond to a request for comment.
Source: https://threatpost.com/ios-exploit-checkm8-could-allow-permanent-iphone-jailbreaks/148762/