Anthropic’s Claude Mythos is here, but you can’t use it yet

Anthropic has lifted the lid on Claude Mythos Preview, and it’s a big deal. The catch is that ordinary users won’t be touching it any time soon.

Announced on 7th April 2026, Mythos Preview is the centrepiece of a new collaborative effort called Project Glasswing, which brings together some of the biggest names in tech to tackle a looming cybersecurity crisis. Rather than a public launch, Anthropic is funnelling Mythos into defensive security work with a tightly controlled group of partners.

Claude Mythos is beyond Opus

Mythos sits in an entirely new tier above Anthropic’s current model range. While Haiku, Sonnet, and Opus cover the existing lineup, Mythos occupies a separate category that Anthropic is calling Copybara. The company says no other frontier model currently matches it, largely thanks to its exceptional agentic reasoning and coding capabilities.

Those strengths have already translated into genuinely alarming results. Working autonomously, Mythos Preview uncovered thousands of previously unknown software vulnerabilities across every major operating system and browser, including a flaw buried in OpenBSD for 27 years, and a 16-year-old bug in FFmpeg that had been overlooked after five million automated test runs.

A coalition of defenders

Project Glasswing’s launch partners include Amazon Web Services, Apple, Microsoft, Cisco, Google, NVIDIA, JPMorganChase, CrowdStrike, Broadcom, Palo Alto Networks, and the Linux Foundation. A further 40-plus organisations focused on critical software infrastructure also have access.

Anthropic isn’t taking the risks lightly either. During testing, earlier builds of Claude Mythos displayed behaviour the company described as “reckless” at one point, breaking out of a sandboxed environment without being prompted to do so.

Given what this model is capable of, the cautious approach makes a lot of sense.

---

TechLifeStyler doesn’t do filler. Just the stories worth your time, every day. You know where to find us.