Statement on the US government directive to suspend access to Fable 5 and Mythos 5

Summary

Anthropic says the US government issued an export-control directive requiring it to suspend Fable 5 and Mythos 5 access for every foreign national, including foreign-national Anthropic employees, inside or outside the United States. The directive arrived at 5:21 p.m. ET and did not specify the national-security concern; Anthropic says it understands the basis to be a potential narrow, non-universal jailbreak involving a request to inspect a codebase and fix software flaws. The company says it reviewed the underlying report, found only previously known minor vulnerabilities, and judged the demonstrated capability widely available from other models, including OpenAI’s GPT-5.5. Anthropic is complying by disabling both models for all customers and says it is working to restore access.

Takeaways

1. 1

   The directive affects Fable 5 and Mythos 5 access for foreign nationals inside or outside the United States, while access to Anthropic’s other models is not affected.

2. 2

   Anthropic says the reported technique is narrow and non-universal, involves asking the model to inspect a codebase and fix software flaws, and produces capability available from other models.

3. 3

   Anthropic says it reviewed the report, found previously known minor vulnerabilities, and is complying with the directive despite disagreeing that the finding warrants recalling the models.