Claude Mythos Finds a Flaw in a Post-Quantum Signature Scheme and Accelerates an AES Attack by Up to 800x

Anthropic's Claude Mythos Preview identified a previously unknown automorphism flaw in HAWK, a NIST post-quantum signature candidate, cutting its effective key strength in half in roughly 60 hours and $100,000 of compute. The same model developed a technique that speeds up a seven-round AES-128 attack by 200 to 800 times, though neither result threatens production systems today.