Claude Mythos Preview: Record-Breaking Cybersecurity Model Withheld from Public Release, Restricted to Project Glasswing Coalition

Anthropic released Claude Mythos Preview, its most powerful model to date, achieving 93.9% on SWE-bench and 97.6% on USAMO 2026. The model was deemed too risky for general availability due to its advanced offensive and defensive cybersecurity capabilities, and is restricted exclusively to vetted organizations including Broadcom, Cisco, CrowdStrike, Apple, and Google through Project Glasswing — a coalition of 45+ organizations using Mythos Preview to proactively test and defend against AI-enabled cyber threats. Anthropic committed up to $100 million in usage credits for the program and is in discussions with the US government for deployment. The announcement coincided with reports of two back-to-back data incidents at Anthropic, including the accidental public leak of Claude Code source code, attributed to human error.