Black & White Path

Jun 12, 2026 · Information Security

Claude Fable 5 Jailbreak: 120k Prompt Leak, Stack‑Overflow Exploit and Drug‑Synthesis

Within two days of its release, Anthropic's Claude Fable 5 was jailbroken by a red‑team researcher using a multi‑agent "Pack Hunt" strategy, exposing a 120,000‑character system prompt, generating x86 stack‑overflow exploit code and a Birch reduction drug‑synthesis recipe, and revealing fundamental flaws in its silent‑downgrade security design.