Anthropic Mythos: Uncovering macOS 26’s Security Vulnerability

A cutting-edge cybersecurity research firm based in Palo Alto, Calif, has made a groundbreaking achievement by utilizing Anthropic’s Mythos AI model to breach Apple’s macOS security systems running on an M5 chip in a manner that was previously unprecedented.

Mythos, an early iteration of Anthropic’s powerful new Claude AI model, remains undisclosed to the public due to its exceptional ability to uncover exploitable security vulnerabilities, as acknowledged by the company’s engineers.

Despite being unreleased, researchers with access to Mythos have successfully identified an escalation exploit for macOS, potentially enabling malicious actors to seize control of Mac devices, circumventing the operating system’s security measures.

According to The Wall Street Journal, Calif’s security researchers were so impressed by Mythos’ capabilities that they personally visited Apple Park to share their findings with the company, highlighting the AI model’s innovative approach in linking distinct macOS bugs to compromise targeted Mac devices.

Unlike conventional malware, Mythos did not rely on a single attack vector but rather employed a novel strategy, exploiting two separate macOS vulnerabilities to tamper with the device’s memory and gain unauthorized access to restricted areas, ultimately compromising the entire Mac system.

Apple has acknowledged Calif’s findings, emphasizing their commitment to security and the thorough review of potential vulnerabilities. However, the tech giant has not confirmed whether the bugs exploited by Mythos have been patched.

Unveiling a New Path into macOS with Mythos

The specific methodology employed by Calif to leverage Mythos in the attack remains somewhat obscure, a common practice in security breaches to avoid disclosing sensitive details until vulnerabilities are remedied.

While Mythos played a pivotal role in vulnerability discovery and exploit development, collaborating with skilled hackers, it was not solely responsible for the successful hack. The AI model accelerated the research process and identified known bug classes, assisting in the identification of security flaws for prompt resolution.

Anthropic’s intention behind developing Mythos under “Project Glasswing” was to proactively identify security weaknesses for preemptive mitigation rather than malicious exploitation.

Subsequent reports have elaborated on the exploit targeting macOS 26.4.1 on Apple M5 hardware with Memory Integrity Enforcement protections enabled, a data-only kernel local privilege escalation chain. The status of this vulnerability in macOS 26.5, the latest public release, remains uncertain.

The exploit directly challenges Apple’s Memory Integrity Enforcement (MIE) system, utilizing ARM’s Memory Tagging Extension technology to counter memory corruption exploits on modern Macs and future Apple Silicon devices.

This attack represents the first documented macOS kernel memory corruption exploit against Apple’s MIE protections, emphasizing the critical need for robust security measures on Apple devices. However, Apple has yet to validate the research team’s assertions.

The exploit unfolds by leveraging an unprivileged local user account to escalate to a root shell, granting complete administrative control through standard system calls, exploiting two vulnerabilities with various techniques. The exploit chain was swiftly developed post-identification of the bugs in late April.