Access was previously limited to organisations like the US government due to the model’s ability to unearth cybersecurity vulnerabilities
2-MIN READ2-MIN ListenReutersPublished: 4:59am, 10 Jun 2026Anthropic is rolling out a public version of its Mythos AI model, but with guard rails barring its use in risky areas such as cybersecurity, after a preview earlier this year sent shock waves globally with its ability to find software flaws.
The new Claude Fable 5 is the most powerful model Anthropic has ever made for wider use, the start-up said on Tuesday, touting its performance in software engineering and analytics.
Anthropic has so far limited its access to a group of about 200 organisations including the US government under the Glasswing programme, after announcing in April that Mythos had uncovered thousands of software vulnerabilities.
Offering its capabilities more widely may allow the US$965 billion company to extend the momentum that has powered its valuation above rival OpenAI just as the two start-ups at the centre of the AI industry race to go public.
The company said it had done extensive testing to ensure that users could not manipulate the new model to bypass its guidelines and perform restricted actions.
“Let’s say I’m a college student asking the model like help me find cyber vulnerabilities on X package or code. The model would refuse and Fable 5 will fall back to Opus 4.8 for a response,” said Dianne Penn, Anthropic’s head of product management, research and labs.
