Black & White Path

Jun 16, 2026 · Information Security

Claude Fable 5 System Prompt Leaked: 120,000 Characters Exposed on GitHub

In mid‑June 2024 Anthropic released Claude Fable 5, and within 24 hours a hacker posted the model's full 120,000‑character system prompt—covering personas, safety rules, downgrade policies, and more—on the public GitHub repository elder‑plinius/CL4R1T4S, revealing its close relationship with Claude Mythos 5.