As part of Project Glasswing, we’re using @AnthropicAI’s Mythos Preview to find and fix vulnerabilities in our products, strengthening our secure development and response practices to help customers stay resilient. Read more 🔗

Anthropic launched Project Glasswing in April 2026 to tackle a growing cybersecurity problem: software has more security flaws than humans can realistically find and fix. The company gave about 50 organizations early access to a new AI model called Claude Mythos Preview, designed specifically to search for vulnerabilities in code. The results exceeded expectations. >In just one month, the system found more than 10,000 high or critical security vulnerabilities. >Scanning over 1,000 open-source projects uncovered 23,019 total issues >6,202 were rated high or critical severity. >Independent reviewers confirmed that about 90.6% of the findings were real problems. Several organizations reported major discoveries: >Cloudflare identified around 2,000 bugs, including 400 high or critical ones. >Mozilla fixed 271 vulnerabilities in Firefox version 150, more than 10 times the number fixed in the previous release. >The project also rediscovered old flaws, including a 27-year-old vulnerability in OpenBSD and a 16-year-old issue in FFmpeg.

Introducing Project Glasswing: an urgent initiative to help secure the world’s most critical software. It’s powered by our newest frontier model, Claude Mythos Preview, which can find software vulnerabilities better than all but the most skilled humans.

Project Apollo. Project Glasswing. Project Hail Mary. The interesting word isn’t the second one. “Project” — from projicere, to cast forward. Every Project is an act of throwing something into the future and betting it lands. That’s why the word carries weight decades after Apollo and still fits fiction set decades ahead. Projects are where ideas gather force. Plane is where they take shape.​​​​​​​​​​​​​​​​ @planepowers!

ANTHROPIC WILL LET MYTHOS PARTNERS SHARE CYBER FINDINGS Reuters reports Anthropic is revising Project Glasswing rules so partners can share Mythos-related vulnerability findings outside the program. Partners include Amazon, Microsoft, Nvidia and Apple. They can share findings, tools, code and best practices with other companies, regulators, government agencies, industry bodies and open-source maintainers. Mythos is still unreleased and limited to defensive cybersecurity use.

NYSE USED ANTHROPIC’S MYTHOS TO FIND CYBER FLAWS NYSE President Lynn Martin says the exchange used Anthropic’s Project Glasswing to identify multiple vulnerabilities in its cybersecurity systems and fix them quickly. Project Glasswing gives vetted partners early access to Anthropic’s Mythos model for defensive security testing. NYSE did not disclose what the vulnerabilities were or when they were fixed.

The next frontier of AI-secured financial and technological critical infrastructure. @ICE_Markets and @NYSE are part of @AnthropicAI's cyber security initiative Project Glasswing, deploying Anthropic’s Claude Mythos Preview across ICE’s exchanges, clearing houses, mortgage technology and FIDS businesses to identify and remediate vulnerabilities before they can be exploited through emerging AI capabilities. “Working with Anthropic on Project Glasswing, we are advancing our technology-forward innovations while protecting the integrity of our state of the art infrastructure powering the global capital markets,” said @lynnmartin, President, NYSE Group.

Fable 5.1 is imminent. Users are getting routed to Fable 5.1 in Claude right now. The current Fable 5 has been in Project Glasswing since April. That is four months old in an industry that moves every four weeks. We have been using a legacy model and calling it the best in the world. This is not an update. This is going to be a leap.