Anthropic Blocks EU Access to Fable 5 and Mythos 5 Over Security Jailbreak Concerns

According to Bloomberg, Anthropic blocked European Union access to its Fable 5 and Mythos 5 AI models today (June 25) following security vulnerabilities. The Trump administration cited national security concerns, while Anthropic said the restriction followed findings that users could "jailbreak" Fable 5's safeguards. European Commission Executive Vice President Henna Virkkunen expressed concerns that the move blocked European cybersecurity use.

The block disrupts ongoing EU work: Anthropic had approved the European Union Agency for Cybersecurity (ENISA) in early June to test Mythos through Project Glasswing, a restricted program for evaluating vulnerability-finding capabilities before wider release. The access cutoff now halts that evaluation ahead of an EU AI and cybersecurity action plan scheduled for early July.