Anthropic Releases First Public Version Of Claude Mythos—With Major Safeguards

BreakingBusinessBreaking NewsAnthropic Releases First Public Version Of Claude Mythos—With Major SafeguardsByZachary Folk,Forbes Staff. I cover breaking news.Follow AuthorJun 09, 2026, 01:37pm EDTToplineAnthropic released Claude Fable 5 on Tuesday, the first public version of its highly anticipated and highly feared Claude Mythos model—equipped with guardrails to prevent users from using it to exploit cybersecurity vulnerabilities or develop bioweapons.Anthropic said the new version, called Claude Fable 5, will have safeguards to prevent misuse in fields like cybersecurity.Getty ImagesKey FactsThe company also said it would release another more powerful model, Claude Mythos 5, for a “small group of cyberdefenders and infrastructure providers” that already had access to Claude Mythos Preview.Claude Fable 5 and Mythos 5 will be priced at $10 per million input tokens and $25 per million output tokens—roughly twice the price of Anthropic’s most advanced Claude Opus models currently available, but still less than half the price Claude Mythos Preview was available for.Rumors about the expected release began circulating after the Sources newsletter first reported Anthropic was getting ready to release a public version with “substantial guardrails” on Tuesday, which was then also reported by The Information.This is a breaking story and will be updated.Got a tip? Share confidential information with Forbes.Editorial StandardsReprints & PermissionsLOADING VIDEO PLAYER...FORBES’ FEATURED Video