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Anthropic has released the first public version of its Claude Mythos model, now called Fable 5. The launch has triggered debate across crypto markets, where investors, developers, and security experts worry about blockchain security and DeFi risk. The concern comes as Anthropic says the model can find serious software flaws at scale.
Anthropic said earlier this year that Mythos found more than 10,000 high- and critical-severity vulnerabilities in important software projects. That disclosure pushed a new debate about whether such a capable model should reach the public.
The company then released Fable 5 with safeguards meant to reduce misuse. It also said the public version redirects some cybersecurity tasks to Claude Opus 4.8.
Anthropic said the guardrails aim to lower the chance of harmful use. Even so, the release has kept security concerns alive inside the crypto sector.
Moonrock Capital founder Simon Dedic warned that advanced AI could make it easier to find smart contract weaknesses. He said attackers may need less skill and fewer resources to spot flaws in unaudited protocols.
Dedic also urged users to review wallet permissions and reduce exposure to risky protocols. He added that hardware wallets can help protect assets from threats.
Curve Finance co-founder Michael Egorov took a different view. He said Mythos’ success in large software systems may not carry over to smart contracts, which often contain far less code.
Read More: Anthropic Launches Claude Fable 5 with Advanced Safety Controls
Egorov said the bigger threat may come from operational security failures. He pointed to compromised multisignature wallets, supply chain attacks, and weaknesses in frontend dependencies.
Those risks can affect decentralized applications even when smart contracts remain sound. As a result, the debate has widened beyond code review alone.
Anthropic also said a limited group of cybersecurity and infrastructure organizations will receive access to Claude Mythos 5. That version carries fewer restrictions than the public Fable 5 release, which keeps the model within tighter guardrails.
Anthropic’s Fable 5 has drawn fresh attention to crypto security by raising concerns about smart contract risks and operational threats. While safeguards limit misuse, experts remain split on the real danger. The bigger takeaway is that users and developers should stay alert and protect assets carefully
