AI Models

Anthropic Releases Safer Claude Fable 5 AI After Mythos Concerns

Anthropic has released Claude Fable 5, a restricted version of its powerful Mythos AI system. The new model costs twice as much as the previous flagship and includes guardrails to prevent misuse in cybersecurity and biology, after the company warned Mythos could aid hackers.

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Neura Market Editorial

June 9, 20263 min read
Anthropic Releases Safer Claude Fable 5 AI After Mythos Concerns

Anthropic on Tuesday released a restricted version of its powerful Mythos artificial intelligence system, a move that follows concerns that the original technology could be used by hackers to break into computer networks.

The new model, called Claude Fable 5, is twice as expensive as Anthropic's previous flagship system. The company said it includes additional guardrails designed to block responses related to cybersecurity, biology and other vulnerable areas.

A Delayed Release Over Security Fears

In April, Anthropic introduced Claude Mythos, a new AI system. But the company said it could not share Mythos with the public because the technology could become a powerful tool for hackers looking to penetrate computer networks. That warning alarmed executives and government officials who feared the system could trigger a new era of cybersecurity threats.

Now, with Claude Fable 5, Anthropic is offering a version that researchers believe is safe for widespread use. The company said Fable relies on older technology for some of its functions, which reduces its capabilities.

How Claude Fable 5 Differs

Because of the guardrails built into Claude Fable 5, hackers may find it difficult to use the system to attack computer networks. However, the same safeguards mean that businesses and cybersecurity experts may also struggle to use Fable to defend networks.

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When Claude users submit queries in areas that could be perceived as too risky, Anthropic said, those queries will be handled by Claude Opus 4.8. That model was released last month and was also designed to avoid the security risks of Mythos.

Anthropic's head of product management, Dianne Penn, explained the reasoning behind the approach. "That is the core of why we have been able to release Fable," she said.

Expanded Access to Mythos

Anthropic initially shared the full Mythos system with about 40 organizations that maintain critical computer infrastructure. Those groups used Mythos to patch security vulnerabilities before hackers could exploit them. This month, the company said it would expand access to Mythos to 150 additional organizations.

Anthropic is an AI safety company founded by former OpenAI employees. The company has developed a series of AI models under the Claude brand, with a focus on responsible deployment. The release of Claude Fable 5 represents a compromise between making advanced AI available and managing the risks of misuse.

The decision to restrict Mythos and offer a safer alternative highlights the ongoing tension between innovation and safety in the AI industry. Government regulators have been paying close attention to these developments, and the White House has issued executive orders related to AI security in recent years.

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