Mozilla used Anthropic's Claude Opus 4.6 and Claude Mythos Preview to scan Firefox for security vulnerabilities, identifying hundreds of previously-unknown bugs. Firefox 150, released this week, includes fixes for 271 vulnerabilities discovered through this collaboration. The finding demonstrates AI's emerging role in security vulnerability discovery and suggests defenders now have powerful new tools to harden critical software.
Safety
The zero-days are numbered
Claude Opus 4.6 helped Mozilla uncover 271 previously-hidden Firefox vulnerabilities, demonstrating AI's emerging power as a security hardening tool for critical software.
Tuesday, April 21, 2026 12:00 PM UTC2 MIN READSOURCE: LobstersBY sys://pipeline
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SafetyApr 22
Quoting Bobby Holley
Mozilla and Anthropic discovered 271 Firefox vulnerabilities using Claude Mythos Preview, validating AI's effectiveness for systematic security hardening.
ResearchApr 22
Mythos found 271 Firefox flaws – but none a human couldn’t spot
Mythos, Anthropic's vulnerability-finding AI, discovered 271 flaws in Firefox—far outpacing human researchers—flipping the security economics by making exploit discovery cheap for defenders while eroding attackers' advantage.