Five Years of tachy0n: A Retrospective on an iOS 13.5 0day Exploit

This post reflects on tachy0n, an iOS 13.5 0day exploit released in 2020, leveraging the Lightspeed vulnerability (CVE-2020-9859) discovered by Synacktiv. Author Siguza details the exploit's discovery and its use in jailbreaking, highlighting the race condition in the `lio_listio` syscall. The article also discusses significant security improvements introduced in iOS 14 that effectively mitigated such attacks, shifting Apple's security strategy from patching individual bugs to addressing entire exploitation strategies. This is a technical news report focusing on iOS system security and exploit development.