Why Anthropic suddenly pulled Fable 5 and Mythos 5 for everyone

Anthropic has disabled access to its Fable 5 and Mythos 5 models worldwide after a US government export directive citing national security. Other Claude models remain available, but attempts to select Fable 5 now return a message that the model is currently unavailable.

The company said the government’s communication came as a letter that did not provide specific details of its concern. Anthropic’s understanding is that the government believes it became aware of a method of bypassing, or “jailbreaking,” Fable 5, and that a demonstration showed a “specific technique” used to identify a small number of previously known, minor vulnerabilities.

Anthropic added that the vulnerabilities are “relatively simple” and that other publicly available models can discover them without a bypass.

United States

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