Mozilla Patches 271 Firefox Vulnerabilities Found by Anthropic's Claude Mythos

Mozilla said early access to Anthropic's Mythos Preview model helped it identify 271 security vulnerabilities in this week's release of Firefox 150, a substantial increase from the 22 security-sensitive bugs Anthropic's Opus 4.6 model found in Firefox 148 last month. Firefox CTO Bob Holley noted that the vulnerabilities could have been discovered through automated fuzzing techniques or Anthropic had previously said it was limiting Mythos Preview's initial release to a limited group of critical industry partners. The Mozilla results come amid debate over whether the model represents a significant advance in AI-aided security or is a relatively normal step up in capabilities.