Security researcher Taylor Hornby, who used Anthropic's Claude Opus 4.8 last month to uncover a critical counterfeiting bug in Zcash's Orchard shielded pool, now plans to add Monero to his audit queue. The revelation sent XMR tumbling nearly 10% in the last 24 hours, trading at $298.76 as of writing — a stark contrast to ZEC's partial recovery to $373.27 after an emergency patch shipped June 2 erased about 30% of its value.
The bug that broke Zcash
Hornby was commissioned by nonprofit developer Shielded Labs in April 2026 to audit Zcash. He ran a custom auditing agent paired with Claude Opus 4.8 on May 29, 2026, and found an under-constrained elliptic curve check in the Orchard shielded pool. The flaw could have allowed an attacker to create unlimited, undetectable counterfeit ZEC. The bug had existed since the Orchard pool launched in May 2022. Hornby's report notes that prior exploitation is considered unlikely but cannot be ruled out cryptographically.
Emergency patch and a 30% haircut
ZEC's price cratered after Hornby disclosed the bug publicly, dropping roughly 30% before developers shipped an emergency patch on June 2. Since then, the token has recovered nearly 20% in the last 24 hours, steadying near $363 before climbing to $373.27. The recovery is partial — the coin still hasn't regained its pre-disclosure levels.
Monero in the crosshairs
Hornby intends to apply for a Zcash coinholder grant to fund a formal audit of Monero. Monero's privacy-focused codebase is notoriously complex, and Hornby's track record suggests he won't go easy. The XMR price drop — nearly 10% on the news — reflects market jitters that another critical flaw could surface.
The Winklevoss push for formal verification
A formal verification push backed by the Winklevoss twins now aims to prevent similar flaws in Zcash. The idea: mathematically prove the correctness of the shielded pool logic so that bugs like the under-constrained curve check can't slip through again. Whether that effort will extend to Monero is unclear, but Hornby's audit might serve as a roadmap for where formal methods are most needed.
Hornby's next step is submitting his grant proposal to Zcash coinholders. If funded, the Monero audit could begin within weeks. The crypto community will be watching to see if Claude Opus 4.8 strikes twice.
