Claude Mythos 5
The same underlying model as Claude Fable 5 with its cyber safeguards lifted, launched for a small group of cyberdefenders and infrastructure providers through Project Glasswing, in collaboration with the US government
Claude Mythos 5
Anthropic • June 2026
Training Data
Not disclosed
Claude Mythos 5
June 2026
Parameters
Not disclosed
Training Method
Same weights as Fable 5, deployed with cyber safeguards lifted for vetted partners
Context Window
1,000,000 tokens
Knowledge Cutoff
January 2026
Key Features
Project Glasswing Only • Same Model as Fable 5 • Cyber Safeguards Lifted
Capabilities
Security: Outstanding
Life Sciences: Outstanding
Reasoning: Outstanding
What's New in This Version
Described by Anthropic at launch as having the strongest cybersecurity capabilities of any model in the world, at $10/$50 per 1M tokens — less than half the price of Mythos Preview; a separate biology program was announced with biology and chemistry safeguards removed but cyber safeguards kept
The same underlying model as Claude Fable 5 with its cyber safeguards lifted, launched for a small group of cyberdefenders and infrastructure providers through Project Glasswing, in collaboration with the US government
What's New in This Version
Described by Anthropic at launch as having the strongest cybersecurity capabilities of any model in the world, at $10/$50 per 1M tokens — less than half the price of Mythos Preview; a separate biology program was announced with biology and chemistry safeguards removed but cyber safeguards kept
Technical Specifications
Key Features
Capabilities
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