Anthropic unveils Mythos cybersecurity model weeks after Claude Code leak exposed security lapse

Anthropic on Tuesday unveiled Claude Mythos Preview, a new frontier AI model built for cybersecurity work, and launched Project Glasswing, a partner program that gives a small group of major technology and infrastructure organizations early access to the system for defensive security tasks.

Anthropic said the unreleased model has already found thousands of high-severity vulnerabilities across major operating systems and web browsers, and described the effort as an urgent push to put advanced cyber capabilities in defenders’ hands before attackers gain similar tools.

Project Glasswing includes AWS, Apple, Broadcom, Cisco, CrowdStrike, Google, JPMorganChase, the Linux Foundation, Microsoft, Nvidia, and Palo Alto Networks, with more than 40 additional organizations also getting access. Anthropic said it is committing up to $100 million in usage credits and $4 million in donations to open source security groups as part of the program.

Anthropic said the model can identify vulnerabilities and develop related exploits with little or no human steering, and highlighted examples including a 27-year-old OpenBSD flaw, a 16-year-old FFmpeg bug, and chained Linux kernel vulnerabilities that could escalate ordinary user access into full machine control. Anthropic’s announcement says the relevant bugs have already been patched.

The Mythos launch lands barely a week after Anthropic created its own security mess by accidentally exposing Claude’s code source files through a packaging error in version 2.1.88 of its software. The mistake exposed nearly 2,000 files and more than 500,000 lines of code, then spiraled further when Anthropic’s takedown effort accidentally hit around 8,100 GitHub repositories before the company reversed most of the notices.

Anthropic is now presenting Mythos as a model so capable and potentially dangerous that it will not be released broadly for now. In the Project Glasswing materials, the company says it does not plan to make Mythos Preview generally available and instead wants to develop safeguards first so Mythos class models can eventually be deployed more safely at scale.

A leaked internal document described Mythos as the company’s most capable model to date and as a meaningful step change in reasoning, coding, and cybersecurity. Anthropic has also been discussing the model’s offensive and defensive cyber implications with US government officials.