Anthropic's Mythos model finds 13x more bugs in Firefox
mozilla security researchers report that anthropic's mythos model significantly improved vulnerability detection. firefox shipped 423 bug fixes in april 2026, up from 31 a year prior. the model found critical sandbox vulnerabilities and dormant code errors older than 15 years.
Mozilla security researchers disclosed that Anthropic's Mythos model drastically increased vulnerability detection in Firefox. The browser shipped 423 bug fixes in April 2026, a thirteen-fold increase from the 31 fixes shipped in April 2025. The agentic system identified high-severity bugs, including critical sandbox vulnerabilities and errors dormant for over 15 years, by generating compromised patches to test security limits. Despite improved detection, Mozilla has not automated the fixing process; human engineers still write and review every patch.