Brian Grinstead

Firefox deployed an AI-assisted hardening pipeline using Claude Mythos Preview, surfacing hundreds of security bugs (271 via Mythos, 423 total fixed in April) and tying fixes to CVEs while outlining a scalable workflow and CI integration.

Mozilla says Mythos identified 271 Firefox vulnerabilities in two months with almost no false positives, aided by a custom harness and model improvements.

Anthropic's Mythos dramatically improves vulnerability discovery in Firefox, with Mozilla reporting 423 fixes in April 2026 versus 31 a year earlier, highlighting a shift in security tooling and disclosure dynamics.