Researcher Who Found Zcash Flaw Adds Monero; XMR Drops 10%

Taylor Hornby, the security researcher who used Anthropic’s Opus 4.8 to expose a critical Zcash flaw, confirmed plans to add Monero to his audit queue. After the announcement, Monero’s XMR traded around $298.76, down roughly 10%.

Hornby was commissioned by nonprofit developer Shielded Labs in April to run an AI-assisted audit of Zcash. On May 29 he ran a custom auditing agent paired with Opus 4.8 and flagged a soundness flaw in Zcash’s Orchard shielded pool within a day. Engineers issued an emergency patch on June 2.

The flaw was an under-constrained elliptic curve check in Orchard that has been in the code since Orchard launched in May 2022. If exploited, the bug could have allowed the creation of undetectable, unlimited ZEC inside the shielded pool. Shielded Labs wrote that prior exploitation looks unlikely but cannot be ruled out on purely cryptographic grounds.

The Zcash token fell sharply after the disclosure, dropping as much as about 30% before partially recovering. ZEC traded near $373.27 at the time of writing.

Hornby announced additions to his audit queue on the social platform X, posting “Absolutely! I’ll add Monero to my queue of things to audit.” He also wrote that he will apply for a Zcash coinholder grant to fund the work and posted public donation addresses.

Monero differs from Zcash because privacy is the default: every Monero transaction is private by design rather than optional. A recent Monero network upgrade added additional privacy features, increasing the code and cryptographic material available for review.

A formal verification effort backed by the Winklevoss twins has begun work following the Zcash disclosure. Hornby and other auditors are expected to continue reviews over the coming weeks as developers work to confirm the absence of exploitable weaknesses.