From Decrypt · By Jose Antonio Lanz
In brief
Calif showed an untethered iOS 27.0.1 jailbreak on an iPhone 18 Pro at Hexacon in Paris on October 16, with root access returning after a reboot.
The firm has not named the vulnerabilities or released a tool, and says it will publish everything later.
Apple's iOS 27 security notes credit Calif.io, working with Claude and Anthropic Research, for two unrelated crash bugs; Apple has not commented on the demo.
Security firm Calif.io demonstrated an untethered jailbreak on an iPhone 18 Pro running iOS 27.0.1 on stage at Hexacon, the offensive security conference in Paris, on Friday. It's the first time an untethered, permanent jailbreak is successful in such devices.
A jailbreak strips away Apple's software restrictions, and untethered means it comes back on its own after a restart, with no computer attached.
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Apple builds the iPhone as a locked-down system, with signed code, a sandbox around every app and a protected startup chain, so owners cannot change how iOS works or run software the company has not allowed. A jailbreak breaks that lock and hands the user root access, which lets them install apps Apple never approved, add new features, customize the interface and use the phone in ways Apple did not intend.
For example, back in the early iOS days, users with jailbroken phones were capable of filming video before Apple shipped that feature. They were also able to run Android on their iPhones, unlock carriers, install themes, and so on. Right now a user with a jailbroken iPhone can install apps outside of the Appstore, browse the full file system and delete bloatware.
Few people do this today, but every working jailbreak on current hardware shows that the defenses Apple invests heavily in can still be beaten.
Video from the stage, posted by jailbreak researcher Billy Ellis, shows the team rebooting the phone, unlocking it with the regular passcode and opening an SSH session as root, the highest level of access on the device. The terminal output listed iOS 27.0.1 and an uptime of about two minutes.
At #hexacon - https://t.co/jEOpspETlT demos iOS 27.0.1 untethered jailbreak on iPhone 18 Pro pic.twitter.com/S54aRrzHFS
— Billy Ellis (@bellis1000) October 16, 2026
Hexacon runs October 16 and 17 in Paris, so the demo came on the opening day of the conference. The event is aimed at researchers who find and exploit security flaws, and its talks typically cover bugs in widely used platforms such as phones and browsers.
Calif has not said which vulnerabilities it used, and no public tool exists. Its newsletter post from the conference lists four demos, including a Signal one-click and an iMessage demo, and says everything “will be released in due time.”