Anthropic Releases Guardrailed Mythos Model 'Claude Fable 5' Publicly

On June 9, 2026, Anthropic released Claude Fable 5, a publicly available version of its frontier internal Mythos-class models fitted with added safety measures. It became immediately available to paid subscribers and enterprise customers, with same-day support for IDE integrations such as Cursor. The top-tier Claude Mythos 5 remains restricted to Project Glasswing, a trusted-partner program that includes Microsoft, Google, Apple and AWS. Alongside the official announcement, major outlets including CNBC and the NYT reported the launch.