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NewsDigital Assets

Anthropic's Fable 5 Launch Puts Crypto Security on Alert

Anthropic released Fable 5 — its publicly available version of the Claude Mythos AI model — and the crypto community is not waiting to react. The model's earlier iteration flagged more than 10,000 high- and critical-severity vulnerabilities across systemically important software, a disclosure that had already unsettled DeFi developers and security researchers before the public launch. Anthropic built in guardrails, but industry voices remain split on how much the risk has actually been contained.

By Renata OstrowskiDigital Assets DeskJune 19, 20262 min read
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Key takeaways

  • Anthropic released Fable 5, the public version of its Claude Mythos AI model, prompting immediate reaction from the crypto security community.
  • An earlier iteration of the model flagged more than 10,000 high- and critical-severity vulnerabilities across systemically important software.
  • Moonrock Capital's Simon Dedic warned the tool could lower the skill barrier for finding smart contract exploits and urged users to audit wallet permissions, reduce exposure to risky protocols, and use hardware wallets.
  • Curve Finance co-founder Michael Egorov downplayed the smart contract threat, arguing the greater danger lies in infrastructure like multisignature wallets and frontend supply chain attacks.
  • Anthropic is using a two-tier release, giving select cybersecurity and infrastructure organizations a less-constrained Claude Mythos 5 while routing certain cybersecurity tasks in the public Fable 5 to Claude Opus 4.8.

Anthropic released Fable 5 — its publicly available version of the Claude Mythos AI model — and the crypto community is not waiting to react. The model's earlier iteration flagged more than 10,000 high- and critical-severity vulnerabilities across systemically important software, a disclosure that had already unsettled DeFi developers and security researchers before the public launch. Anthropic built in guardrails, but industry voices remain split on how much the risk has actually been contained.

Smart Contract Exposure: The Case for Concern

Moonrock Capital founder Simon Dedic argued that tools like Fable 5 could compress the skill barrier for identifying exploitable weaknesses in smart contracts. Unaudited protocols, he warned, face a meaningful new threat as automated systems grow capable of doing at scale what once required specialist knowledge. Dedic offered concrete defensive steps for users: audit wallet permissions, reduce exposure to higher-risk protocols, and move assets to hardware wallets.

The Counter-Argument: Smart Contracts Are Not Enterprise Code

Curve Finance co-founder Michael Egorov pushed back on the scale of the threat, at least where smart contracts are concerned. The environments where Mythos demonstrated its vulnerability-finding capabilities — traditional software stacks — can run to millions of lines of code. Smart contracts, by contrast, are compact enough that both human auditors and existing AI tools already cover them reasonably well. The comparison, Egorov suggested, does not map cleanly from one domain to the other.

Where Egorov Does See Risk

Infrastructure, not code logic, is where Egorov located the more pressing danger. Compromised multisignature wallets, supply chain attacks targeting frontend dependencies, and other weaknesses in the systems that surround decentralized applications represent the attack surface he considers more likely to give way. Those vectors do not require cracking smart contract bytecode — they exploit the human and operational layers underneath.

A Two-Tier Release Structure

Anthropic is not issuing a single version of Mythos. A restricted cohort of cybersecurity and infrastructure organizations will receive access to Claude Mythos 5, a configuration that operates with fewer constraints than the public Fable 5 release. For the general build, the company acknowledged the inherent risks of a model with advanced vulnerability-discovery capabilities and confirmed that certain cybersecurity-related tasks are redirected to Claude Opus 4.8 rather than handled by Fable 5 directly.

Related reading

About this story

Filed by the digital assets desk of MarketPR on June 19, 2026. Source: coinpaper.com. Indicative figures are not investment advice.

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Frequently asked

What is Fable 5?

Fable 5 is Anthropic's publicly available version of its Claude Mythos AI model, which has advanced vulnerability-discovery capabilities.

Why is the crypto community concerned about Fable 5?

Because an earlier iteration flagged over 10,000 high- and critical-severity software vulnerabilities, and observers like Simon Dedic fear it could make it easier to identify exploitable weaknesses in unaudited smart contracts.

Does Michael Egorov think smart contracts are at high risk?

No; Egorov argues smart contracts are compact and already well covered by human auditors and existing AI tools, unlike the millions of lines of traditional software where the model proved its capabilities.

Where does Egorov see the real risk?

In infrastructure rather than code logic, citing compromised multisignature wallets, supply chain attacks on frontend dependencies, and other weaknesses in the human and operational layers around decentralized apps.

How is Anthropic structuring the Mythos release?

It is a two-tier release: a restricted cohort of cybersecurity and infrastructure organizations gets the less-constrained Claude Mythos 5, while the public Fable 5 redirects certain cybersecurity tasks to Claude Opus 4.8.