Anthropic's Mythos Shown to Weaponize Disclosed Flaws Within Hours

Anthropic's frontier model "Claude Mythos Preview" has demonstrated the ability to autonomously weaponize newly disclosed vulnerabilities (n-days) within hours. According to Anthropic research published around June 8, 2026, the model built a working exploit within an hour of Mozilla releasing a Firefox patch. With cases where a patch takes 18 days to reach user devices, the window opened by the gap between a fix going public and being applied is described as wide enough to exploit.