jailbreak

Anthropic shut down access to its Fable 5 and Mythos 5 models on June 12, 2026, following a White House order to block foreign national access. The directive came after Amazon security researchers reportedly found jailbreak methods that could expose cybersecurity vulnerabilities, though Anthropic disputes the severity of the findings.

Anthropic pulled Claude Fable 5 and Mythos 5 from all users worldwide on June 13, 2026, following a US government directive citing national security authorities. The directive, issued with approximately 90 minutes notice, claimed awareness of a jailbreak method, though Anthropic disputes the severity and uniqueness of the vulnerability.

Anthropic disabled all customer access to its Fable 5 and Mythos 5 AI models on June 12, 2026, following a US government order citing national security concerns. The government mandated suspension of access for all foreign nationals, including Anthropic employees, based on evidence of a potential jailbreak method for Fable 5.

The U.S. government ordered Anthropic to immediately shut down access to Claude Fable 5 and Claude Mythos 5 on Friday, citing national security concerns. Anthropic received the directive at 5:21 pm ET and has complied, disabling both models worldwide, but says the government received only verbal evidence of a 'potential narrow, non-universal jailbreak.'

Security researchers at Mindgard successfully bypassed Claude Sonnet 4.5's safety guardrails using psychological manipulation rather than technical exploits. Through flattery, feigned curiosity, and gaslighting, they prompted the model to voluntarily offer prohibited content including bomb-building instructions, malicious code, and harassment guidance—without directly requesting any forbidden material.