Anthropic Claude Mythos Discovers 271 Vulnerabilities in Firefox Browser

According to Decrypt, Mozilla recently revealed that Anthropic’s latest AI model, Claude Mythos, identified 271 security vulnerabilities during internal testing of the Firefox browser; all related vulnerabilities were patched this week. For comparison, a previous Anthropic model had detected only 22 security-sensitive vulnerabilities. Mozilla stated that all discovered vulnerabilities fell within the scope of what top human researchers could identify. Claude Mythos was officially launched in March 2026 and is Anthropic’s most powerful model to date for reasoning, coding, and cybersecurity. It is currently available exclusively to vetted partners—including Amazon, Apple, and Microsoft—under Anthropic’s “Project Glasswing” initiative.