Claude Mythos Finds 271 Firefox Vulnerabilities in Single Evaluation Pass — Mozilla CTO Says 'As Capable as Elite Security Researchers'

SecurityWeek·high signal

Mozilla patched 271 Firefox vulnerabilities discovered by Anthropic's Claude Mythos in a single evaluation pass, shipping fixes in Firefox 150. Over 40 CVEs were issued, with Mozilla's CTO stating Mythos is 'every bit as capable as the world's best security researchers.' For context, Claude Opus 4.6 found only 22 bugs in Firefox 148 — a 12x improvement that validates Mythos' agentic security capabilities.