
Anthropic Accidentally Leaks 'Claude Mythos' — A Model It Calls a 'Step Change' in AI Power
A misconfigured content management system exposed nearly 3,000 internal Anthropic documents, revealing a new model codenamed 'Claude Mythos' (or 'Capybara') that dramatically outperforms Claude Opus 4.6 on coding, reasoning, and cybersecurity benchmarks. Anthropic confirmed the model is real and already being tested with select customers. The leaked internal safety docs warn it could significantly accelerate cyber arms races by rapidly finding and exploiting software vulnerabilities — making this as much a security story as a capability one.


