Anthropic Launches Project Glasswing: Claude Mythos Finds Thousands of Zero-Day Vulnerabilities Across Major OS and Browsers

Anthropic·high signal

Anthropic announced Project Glasswing, a cybersecurity initiative using its unreleased Claude Mythos Preview model, which discovered thousands of high-severity zero-day vulnerabilities in every major operating system and web browser — including a 27-year-old OpenBSD bug and a 16-year-old FFmpeg flaw. Twelve launch partners including AWS, Apple, Microsoft, Google, CrowdStrike, and JPMorgan Chase are participating, with Anthropic committing $100M in usage credits and $4M to open-source security organizations. The model scored 83.1% on vulnerability reproduction (vs. 66.6% for Claude Opus 4.6) and autonomously chained four vulnerabilities into a browser sandbox escape — Anthropic says it will not be publicly released due to misuse risk.