Claude Opus Found a Four-Year-Old Hole in Zcash’s Privacy Layer. Nobody Knows If Someone Already Used It.

**Executive summary:** A four-year-old critical flaw in Zcash's Orchard shielded pool was discovered using Anthropic Opus 4.8; the vulnerability could have allowed creation of counterfeit ZEC that would appear valid and remain undetectable, prompting an emergency fix on June 1, 2026 and proposals for a network upgrade to verify supply integrity.