Claude Mythos AI Model Uncovers 271 Zero

Cybersecuritynews •Guru Baran • April 22, 2026

Anthropic’s latest frontier AI model, Claude Mythos Preview, has identified a staggering 271 zero-day vulnerabilities in Mozilla Firefox marking a seismic shift in AI-powered cybersecurity defense. The findings, addressed in Firefox 150, represent the most significant single batch of security fixes in the browser’s history. The discovery didn’t happen in isolation. Since February 2026, Mozilla’s […]

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AI Model Claude Mythos Identifies 271 Vulnerabilities in Firefox Mozilla has reported that Anthropic's Claude Mythos AI model discovered 271 vulnerabilities in the Firefox browser during internal testing. This significant finding comes as part of the release of Firefox 150, following an earlier test with Anthropic's Opus model that identified 22 vulnerabilities. Mozilla's CTO Bobby Holley expressed concerns about the sheer volume of vulnerabilities found, indicating a sense of 'vertigo' among the team. Despite the impressive capabilities of Mythos, Holley noted that all vulnerabilities identified could have been found by elite human researchers. The AI's ability to analyze large codebases represents a potential shift in cybersecurity, allowing developers to identify and patch vulnerabilities before they can be exploited. However, the cybersecurity community remains cautious, acknowledging that the complete elimination of vulnerabilities is an unrealistic goal. The findings reflect a growing trend of leveraging AI in cybersecurity to enhance defense mechanisms against potential threats. 29 sources 28

Claude Mythos AI Model Uncovers 271 Zero

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