Claude Mythos AI Model Uncovers 271 Zero-Day Vulnerabilities in Firefox

Mozilla released Firefox 150 to remediate 271 zero-day vulnerabilities discovered through a collaboration with Anthropic, where the Claude Mythos Preview AI model dramatically accelerated code analysis compared to prior models. The report frames the effort as a successful, large-scale AI-assisted vulnerability discovery and remediation exercise, noting the issues were not novel vulnerability classes and highlighting AI's potential to change how defenders find and fix flaws.