Anthropic's Fable 5 is back — and safety filters now block harmless code

anthropic lifted the suspension on fable 5 following a two-week government investigation into a vulnerability that allowed the model to generate software exploits. the fix involved training a classifier that blocks the specific jailbreak technique in over 99 percent of cases, though users will experience increased refusals on routine coding tasks. the less restricted mythos 5 remains limited to us government-approved partners, while anthropic admits making models impervious to jailbreaks is probably impossible. the company is establishing a 24/7 monitoring team and a hackerone program to handle future vulnerabilities, signaling a shift toward tighter government integration on frontier model safety.