What is Claude Mythos? Anthropic’s most powerful AI model yet that’s too dangerous to release publicly

The AI company Anthropic has revealed its latest and most powerful large language model and it’s called Claude Mythos Preview. It’s the most capable LLM it has ever built, and so powerful that the company is keeping it from public use.

Anthropic hopes Mythos can be used by key technology infrastructure organisations and governments to lock down cyber security before tools of this power make it into the public realm. Here’s a brief look at Claude Mythos and the purpose of its new Project Glasswing initiative, which has Apple, Amazon and more than 40 other big hitters on board..

What is Claude Mythos?

The Claude Mythos Preview is a new frontier model that Anthropic has trained, with the goal of securing the most important software on the planet. The cybersecurity nous is so strong that Anthropic’s own engineers found the model able to uncover find dozens of exploits in every major operating system and web browser. Anthropic says Claude Mythos found “thousands of zero-say vulnerabilities, many of them critical” without any human guidance.

For example: “Mythos Preview found a 27-year-old vulnerability in OpenBSD—which has a reputation as one of the most security-hardened operating systems in the world and is used to run firewalls and other critical infrastructure. The vulnerability allowed an attacker to remotely crash any machine running the operating system just by connecting to it.”

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Indeed, Claude Mythos is so powerful that it is likely to outpace all efforts to keep software secure, especially with the rapid proliferation of AI tools. So, that would make it highly responsible to release Claude Mythos into the public realm, given nefarious actors wound undoubtedly leverage the capabilities to advance their own evil doing.

Or, as Anthropic puts it: “The fallout—for economies, public safety, and national security—could be severe.”

What is Anthropic doing about it?

Instead of releasing the AI model into the public sphere, the company has teamed up with 40 of the most important tech companies and financial institutions in the world to offer access. They can use Mythos to scan their own first-party software for vulnerabilities and then plug those potential exploits.

This initiative is called Project Glasswing and involves Amazon Web Services, Anthropic, Apple, Broadcom, Cisco, CrowdStrike, Google, JPMorganChase, the Linux Foundation, Microsoft, NVIDIA, and Palo Alto Networks. Those companies who are deploying Mythos Preview have experienced 83.1% vulnerability protection, compared to the 66.6% protection provided by the Opus 4.6 model.

The company says its fledgling efforts are just the beginning. Anthropic writes: We intend for this work to grow in scope and continue for many months, and we’ll share as much as we can so that other organisations can apply the lessons to their own security. Partners will, to the extent they’re able, share information and best practices with each other; within 90 days, Anthropic will report publicly on what we’ve learned, as well as the vulnerabilities fixed and improvements made that can be disclosed. We will also collaborate with leading security organisations to produce a set of practical recommendations for how security practices should evolve in the AI era. This will potentially include:

Vulnerability disclosure processes;
Software update processes;
Open-source and supply-chain security;
Software development lifecycle and secure-by-design practices;
Standards for regulated industries;
Triage scaling and automation; and
Patching automation.”