Claude Mythos is an unreleased, next-generation AI model from Anthropic that came to light not through an official announcement, but through an accidental data leak in late March 2026.
What is it?
The leaked draft describes Claude Mythos under the internal codename “Capybara.” It would represent a new model tier that sits above Anthropic’s current flagship Opus line — larger and more intelligent — adding a fourth, pricier tier above Haiku, Sonnet, and Opus.
Key features
It scores “dramatically higher” than Claude Opus 4.6 on tests of software coding, academic reasoning, and cybersecurity.
<ul>
<li>Advanced autonomy: Where prior models respond to instructions one step at a time, Mythos plans and executes sequences of actions on its own, moving across systems, making decisions and completing operations without waiting for human input at each stage.</li>
<li>Recursive self-correction: Mythos could autonomously identify its own errors, re-evaluate its starting assumptions, and correct its output without requiring an intermediate human prompt — not a simple chain-of-thought, but a verification loop integrated into the model’s architecture.</li>
<li>Unprecedented cybersecurity capabilities: The draft describes the model as “currently far ahead of any other AI model in cyber capabilities” and warns it presages an upcoming wave of models that can exploit vulnerabilities.</li>
</ul>
Conclusion
Claude Mythos is a very powerful but not yet publicly available model. No official release date has been announced.

Anubhav Bhatt

An unreleased Anthropic AI model codenamed 'Capybara' and publicly referred to as Claude Mythos was revealed through an accidental data leak in late March 2026. It would sit above the current Opus tier, making it a fourth pricing tier above Haiku, Sonnet, and Opus. Key claimed capabilities include dramatically higher scores on coding, academic reasoning, and cybersecurity benchmarks compared to Claude Opus 4.6, advanced multi-step autonomous action execution, recursive self-correction without human prompts, and unprecedented cybersecurity exploitation capabilities. No official release date has been announced.

Claude Mythos — next-generation AI model from Anthropic