Anthropic released Fable, a public version of its cybersecurity-focused Mythos model, but security researchers are criticizing its guardrails as overly aggressive, saying the model rejects even innocuous requests like reading a blog post or reviewing code. Experts complain the restrictions appear keyword-based, flagging anything related to cybersecurity or biology, though some acknowledge the cautious approach is understandable in early deployment and expect the guardrails to relax over time. Anthropic, which built the limits to prevent misuse for malware or biological weapons, also offers a Cyber Verification Program granting approved professionals fewer restrictions.