Anthropic Just Did Something Unprecedented: They Hid Their Best Security Model

Today Anthropic announced Claude Mythos — a model so good at finding security vulnerabilities that they decided not to release it. Instead, they launched Project Glasswing: a restricted program that gives access only to vetted security researchers and major tech companies. The model has already found vulnerabilities in every major operating system and web browser , including a 27-year-old bug in OpenBSD. This is not a marketing stunt. What Makes Mythos Different Claude Opus 4.6 had a near-0% success rate at autonomous exploit development. Mythos Preview developed working exploits 181 times out of hundreds of attempts on the same test cases. Nicholas Carlini from Anthropic said he found more bugs in the last couple weeks than in his entire career combined. Thats not hyperbole — the OpenBSD vulnerability they discovered has been in the codebase for 27 years. The model can: Chain 4-5 vulnerabilities together into sophisticated exploit chains Write JIT heap sprays that escape browser AND O