The name Mythos sounds like it's about to cause some trouble, with top-notch security offense and defense capabilities, but for now, it's just for white hats to play with. Anthropic's move here is probably worried about getting jailbreak again.

Anthropic announces that Claude Opus 4.8 has achieved breakthroughs in security defenses, with the fastest rollout of Mythos-level models to all customers within a few weeks; but Glasswing reports that Mythos will not be publicly available until stronger security measures are in place. Mythos has long-term high offensive and defensive capabilities, with public access limited by the time gap for vulnerability discovery and patching. To prevent abuse, Anthropic is providing qualified security teams with scanning orchestration tools to enhance defenses and establish an asymmetric advantage.