Anthropic disabled Mythos 5 and Fable 5 after a US Commerce Department export-control order barred their use abroad. The administration asked for a pause amid reports of a narrow jailbreak letting Fable 5 analyze code for vulnerabilities. Anthropic says the issue produced only minor findings and that other models, like GPT-5.5, have similar capabilities.

• Anthropic disabled Mythos 5 and Fable 5 days after launch due to a Commerce Department export-control order barring their use outside the US.
• The trigger was a narrow jailbreak letting Fable 5 give cybersecurity/chemistry/biology advice on a specific codebase, but it only surfaced minor vulnerabilities.
• Anthropic claims other models like GPT-5.5 have similar capabilities, suggesting the singling-out of Fable 5 is inconsistent.
• The article's own account is internally contradictory: it names the Commerce Department order as Trump-administration action but then attributes the pause to "the Biden administration."