'This work is a glimpse of what is coming': Security team lays out how Anthropic Mythos helped build a working macOS exploit in five days

Date:
Fri, 15 May 2026 18:15:00 +0000

Description:
A product that took five years to build was broken into in five days, thanks to Mythos - and now Apple is working on a fix.

FULL STORY ======================================================================Copy link Facebook X Whatsapp Reddit Pinterest Flipboard Threads Email Share this article 0 Join the conversation Follow us Add us as a preferred source on Google Newsletter Subscribe to our newsletter Calif researchers used Anthropics Mythos Preview to chain two bugs and techniques into a macOS
kernel exploit on Apple M5 The exploit bypassed Apples new Memory Integrity Enforcement, achieving root shell in five days despite years of Apple investment Attack highlights Mythos power in surfacing unknown flaws; Apple
is reportedly working on a fix Cybersecurity researchers Calif have explained how they used Anthropics (now) famed Mythos Preview AI tool to create a working macOS kernel memory corruption exploit on Apple s newest M5 silicon, warning their work was a glimpse of whats coming for hardware and software that was built in a world before Mythos Preview.

In September 2025, Apple introduced a new security feature designed to block hacking techniques that exploit software memory flaws. Called Memory
Integrity Enforcement (MIE), the feature uses hardware-level memory checks to stop malicious code from accessing data it shouldnt. It was released
alongside the iPhone 17 lineup and the new A19 chips. Latest Videos From You may like Mozillas Mythos AI test could change cybersecurity forever Claude Mythos turns years of security research into 20-hour AI exploits Mythos accessed by unauthorized users as Anthropic says 'Were investigating' Cracks may be showing in Project Glasswing as unknown users access model via third parties Execution model persists In April 2026, Anthropic allowed a handful
of technology companies, including Calif, to access Mythos Preview , so they could get a head start on everyone else and secure their environments.

The company claimed Mythos was capable of surfacing unknown vulnerabilities and creating working exploits and as such was too dangerous to just be released to the general public.

Calif used Mythos to link two bugs and a handful of techniques to corrupt the Macs memory and then gain access to parts of the device that should be inaccessible. Commenting on their findings, the Calif team said Apple spent five years and probably billions of dollars to build MIE, while they managed to break it in five days.

The exploit is a data-only kernel local privilege escalation chain targeting macOS 26.4.1 (25E253), Calif said in a Substack post. It starts from an unprivileged local user, uses only normal system calls, and ends with a root shell. The implementation path involves two vulnerabilities and several techniques, targeting bare-metal M5 hardware with kernel MIE enabled. Are you a pro? Subscribe to our newsletter Sign up to the TechRadar Pro newsletter to get all the top news, opinion, features and guidance your business needs to succeed! Contact me with news and offers from other Future brands Receive email from us on behalf of our trusted partners or sponsors By submitting
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Apparently, Apple is currently working on a fix. Probably using Mythos, too. The best antivirus for all budgets Our top picks, based on real-world testing and comparisons

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