Security researcher Taylor Hornby discovered a critical counterfeiting flaw in Zcash's Orchard shielded pool using Anthropic's Claude Opus 4.8, causing ZEC to drop 30% before an emergency patch. The bug, an under-constrained elliptic curve check, had existed since May 2022 and could have allowed unlimited undetectable minting. Hornby, commissioned by Shielded Labs, will now audit Monero and other privacy coins. Monero's XMR fell nearly 10% on the news, trading at $298.76. The incident highlights AI's role in surfacing long-hidden vulnerabilities.

Key facts

• AI model Claude Opus 4.8 found a soundness flaw in Zcash's Orchard pool, first reported May 29, 2026.
• Bug enabled unlimited undetectable counterfeiting; patched June 2 after 30% ZEC drop.
• Researcher Taylor Hornby will audit Monero and other privacy coins next.
• Monero's XMR fell nearly 10% to $298.76 following the announcement.
• Prior exploitation unlikely but not cryptographically ruled out, per Shielded Labs.