Mozilla’s Firefox Says It Fixed 271 Vulnerabilities With Help From Anthropic’s Mythos

On Tuesday, Mozilla’s free and open-source browser, Firefox, said it had fixed at least 271 vulnerabilities before releasing its latest update, with Mythos, a new AI model from Anthropic with advanced cybersecurity capabilities, helping the team discover these flaws.

Anthropic is not the only company developing AI models focused on identifying software vulnerabilities. Competitors such as OpenAI have also been pushing frontier models in this space, including GPT-5.4-Cyber, a specialized version of its GPT-5.4 model designed specifically for cybersecurity tasks.

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OpenAI just released a specialized AI model built specifically to help security teams find and fix vulnerabilities faster.

TechloyDamilare Odedina

Some researchers see the release of these models as a major breakthrough in AI-assisted security. Critics, however, question whether the technology will make defense easier or simply give attackers more tools to exploit systems. Because of these concerns, Anthropic said it decided not to release Mythos publicly. Instead, the company opted for a limited rollout to a small number of technology and financial organizations under a program called Project Glasswing.

Firefox provides one example of how the model can assist defenders. Using Mythos, Mozilla engineers were able to identify hundreds of vulnerabilities in the browser before shipping the latest release.