Anthropic’s public Fable model frustrates security researchers with broad guardrails on cybersecurity-related prompts

Anthropic released Fable as a limited public version of its powerful cybersecurity model Mythos, but researchers say its restrictions block even benign security tasks. The model can pause chats or fall back to Claude Opus 4.8 when prompts trigger cybersecurity or biology safety filters.

The backlash shows the tension between preventing AI misuse and making advanced models useful for legitimate security work. Overbroad or keyword-driven guardrails could slow adoption among professionals and push the industry toward more nuanced risk-based access systems.

Cybersecurity researchers aren't happy about the guardrails on Anthropic's Fable