Anthropic Announced a Frontier Model Called the "Claude Mythos Preview" to Secure Most Critical Software

IBL News | New York

Anthropic announced yesterday “Project Glasswing,“ a new initiative focused on global safety and security on the software side.

This new AI cybersecurity initiative has already garnered commitments from large technology companies, including Apple, Amazon Web Services, Microsoft, and more.

To enhance their security projects, participant companies that will have the chance to build on Project Glasswing will have access to Claude Mythos Preview, a new general-purpose language model for computer security tasks.

According to Anthropic, “Mythos Preview will help secure the world’s most critical software and prepare the industry for the practices we all will need to adopt to keep ahead of cyberattackers.”

The company said that Mythos Preview already found “thousands of high-severity vulnerabilities” in “every major operating system and web browser,” especially “in real open source codebases.”

Project Glasswing will help companies turn these capabilities “to work” and focus on “defensive purposes” against significant threats.

“Over 99% of the vulnerabilities we’ve found have not yet been patched, so it would be irresponsible for us to disclose details about them (per our coordinated vulnerability disclosure process). Yet even the 1% of bugs we are able to discuss give a clear picture of a substantial leap in what we believe to be the next generation of models’ cybersecurity capabilities—one that warrants substantial coordinated defensive action across the industry. We conclude our post with advice for cyber defenders today, and a call for the industry to begin taking urgent action in response.”

“During our testing, we found that Mythos Preview is capable of identifying and then exploiting zero-day vulnerabilities in every major operating system and every major web browser when directed by a user to do so. The vulnerabilities it finds are often subtle or difficult to detect. Many of them are ten or twenty years old, with the oldest we have found so far being a now-patched 27-year-old bug in OpenBSD—an operating system known primarily for its security.”

“Non-experts can also leverage Mythos Preview to find and exploit sophisticated vulnerabilities. Engineers at Anthropic with no formal security training have asked Mythos Preview to find remote code execution vulnerabilities overnight, and woken up the following morning to a complete, working exploit. In other cases, we’ve had researchers develop scaffolds that allow Mythos Preview to turn vulnerabilities into exploits without any human intervention.”

 

Glasswing is just the first step: patching and securing the world’s software infrastructure will be the work of months and years, and will require even broader cooperation across AI companies, cyberdefenders, software providers, governments, and more.

— Dario Amodei (@DarioAmodei) April 7, 2026