Anthropic's Mythos AI Identifies 271 Zero-Day Vulnerabilities in Firefox 150, Mozilla Reports

Anthropic's Mythos Preview AI model has reportedly identified 271 previously unknown security vulnerabilities in the upcoming Firefox 150 browser, a discovery Mozilla credits with allowing it to patch critical flaws before attackers could exploit them. This significant preemptive find, announced by Mozilla, provides concrete data to the heated debate over whether advanced AI models will empower cyberdefenders or turbocharge hacking capabilities.

Mozilla granted Anthropic early access to the Mythos Preview model, which the AI company had previously touted as exceptionally skilled at finding cybersecurity weaknesses. The model's analysis of Firefox's codebase yielded the 271 zero-day vulnerabilities, which Mozilla has now addressed in the latest browser release. While the exact severity of each flaw was not detailed, the sheer volume of discoveries prompted Firefox Chief Technology Officer Bobby Holley to declare a potential turning point, stating defenders now have a decisive chance to win the ongoing security battle.

The results lend substantial weight to Anthropic's claims about Mythos's capabilities and directly challenge skeptics who viewed the model's launch as mere hype. By demonstrating a tangible, large-scale impact on a major software project, the collaboration signals a shift in how critical infrastructure can be proactively secured. However, it also intensifies scrutiny on the dual-use nature of such powerful AI tools, raising the persistent question of whether this defensive advantage could be reversed if similar models fall into malicious hands.