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Anthropic has released a public version of its Claude Mythos AI model, named Fable 5, which crypto users fear could become a potent tool for exploiting vulnerabilities in decentralized finance (DeFi) protocols. The model, which previously identified over 10,000 high-severity software flaws, is now accessible with safeguards designed to limit misuse. However, those measures have done little to ease concerns in the crypto space.
The AI’s track record is unsettling. Under its Project Glasswing initiative, Mythos discovered critical vulnerabilities across more than 1,000 open-ware like the Linux kernel and FFmpeg. Its ability to identify and even weaponize vulnerabilities—such as generating proof-of-concept exploits for complex issues in under 31 minutes—has raised alarms about its potential misuse, particularly in the high-value crypto sector
DeFi at Risk: Lower Barriers for Exploits
Simon Dedic, co-founder of Moonrock Capital, expressed serious concerns about the implications for DeFi. In a public post, he warned that Fable 5 could drastically lower the cost and expertise required to exploit weaknesses in smart contracts. “Unaudited protocols will become sitting ducks,” Dedic said, adding that the model could lead to a surge in attacks on smaller projects and forks due to the minimal effort required.
Historical data backs his concerns. In April 2026, crypto hacks led to $629.7 million in losses, the highest level seen since early 2025. Analysts have linked this uptick to the use of advanced AI in identifying vulnerabilities. Dedic and other crypto figures are urging users to take defensive measures, such as revoking wallet approvals, moving funds to hardware wallets, and avoiding unaudited protocols.
Guardrails or False Reassurance?
Anthropic has stressed that Fable 5 includes safeguards, such as rerouting cybersecurity-related queries to a less capable AI model, Claude Opus 4.8. The company also limits full Mythos capabilities to vetted cybersecurity organizations. However, critics argue that even restricted access could inadvertently aid malicious actors, especially as AI technology often finds ways to circumvent intended limitations.
Michael Egorov, co-founder of Curve Finance, offered a more tempered perspective. He suggested that Mythos might not significantly impact DeFi code specifically, as smart contracts typically contain fewer lines of code—making them easier for existing AI and human experts to analyze. However, he warned of potential threats in operational security, such as compromises of multisig keys or supply chain attacks on frontend dependencies.
What’s Next?
The release of Fable 5 adds another dimension to the evolving relationship between AI and crypto security. While Anthropic has limited full Mythos access to a “small group” of vetted partners, the broader availability of Fable 5 raises questions about how effectively these safeguards will mitigate risks. For now, the DeFi community faces a stark choice: prioritize comprehensive audits and operational security or risk becoming the next victim of AI-driven exploits.
With DeFi protocols managing billions in assets, the stakes couldn’t be higher. As AI advancements like Claude Mythos continue to redefine cybersecurity, the crypto sector may need to innovate at an equally rapid pace to stay ahead of attackers.
Source: blockchain.news