Apple rains on MIE-bypassing iPhone jailbreak parade with iOS update

Apple’s busy patch week includes iOS 27.2, which closes off most of the bugs security researchers exploited to “jailbreak” an iPhone protected by the company’s newest anti-spyware hardware.

A jailbreak removes the software restrictions Apple places on iPhones, giving users full administrator (root) access to the operating system.

That lets them install apps from outside the App Store and change system files, which is normally a no-no for security purposes.

While jailbreaks provide freedom for users to install the software they want, they can also expose them to malicious code unwittingly, which can access very sensitive information on devices people entrust their digital lives to.

Jailbreaks have become harder to accomplish as Apple has heaped resources on making its devices more secure, but researchers from security vendor Calif recently demonstrated at the Hexacon conference in Paris that they could defeat the protections in iOS and importantly, iPhone hardware.

Security vendor Calif's team was able to run an exploit chain to achieve a jailbreak.

What's more, Esser and team rebooted the iPhone 18 Pro running iOS 27.0.1 and the jailbreak didn't clear out, but survived and was available afterwards.

Esser and Calif's jailbreak got through Apple's hardware Memory Integrity Enforcement (MIE) protection that was introduced with the A19 chips last year.

Calif followed up a week later, jailbreaking Apple's new iPhone Duo on its launch day, October 23, running iOS 27.1 via Signal and Apple iMessage.

At #hexacon - https://t.co/jEOpspETlT demos iOS 27.0.1 untethered jailbreak on iPhone 18 Pro https://t.co/S54aRrzHFS

— Billy Ellis (@bellis1000) October 16, 2026

Apple's iOS 27.2 update, released on October 26, fixed most of the flaws involved, Calif researcher Stefan Esser said, and the security vendor was acknowledged for finding the bugs.

Calif previously said Anthropic's Claude Mythos Preview helped it build a macOS kernel exploit against the MIE protections in Apple's M5 chip in under a week, Decrypt reported.

The delivery route for Calif's jailbreak echoes FORCEDENTRY, the zero-click exploit Citizen Lab caught NSO Group's Pegasus spyware using in 2021, which abused a CoreGraphics flaw through crafted PDF files sent over iMessage.

Calif has not linked its work to any spyware vendor, and has not published technical details of the chain.

AI-assisted research features heavily in the iOS 27.2 notes, which credit Anthropic Research on three fixes and OpenAI on four.

Apple said none of the 163 vulnerabilities fixed in iOS 27.2 was known to have been exploited.

CoreGraphics gets updates, including for old iPhones

Furthermore, Apple has also extended a fix for a separate, exploited CoreGraphics flaw to its oldest supported iPhones, four weeks after patching newer models.

This is a practice known as backporting, as in adding updates for older operating systems, and the iOS 18.7.11 update covers the iPhone XS, XS Max and XR.

Those devices, released in 2018, cannot run the current generation iOS 26 or 27 mobile operating systems.

The update closes CVE-2026-86950, an out-of-bounds write that Apple said could allow arbitrary code execution when processing a maliciously crafted file.

Apple said it was aware of a report that the flaw may have been exploited in "an extremely sophisticated attack against specific targeted individuals" on iOS versions before iOS 27.

It was fixed for iOS 26 and macOS on September 28, but Apple released nothing for handsets limited to iOS 18, even though its warning covered every release before iOS 27.