Zooko Wilcox has reported that a recent security audit of the Zcash protocol conducted by Anthropic and Mythos revealed no significant bugs. This announcement comes at a critical time for the Zcash community, which recently faced a crisis surrounding a major vulnerability in its system.
The vulnerability was uncovered on May 29, 2026, by researcher Taylor Hornby at Shielded Labs. It was a soundness bug within the zero-knowledge proof circuit responsible for Zcash’s Orchard shielded pool. This issue had been present since the Orchard feature activated in May 2022, leaving the network exposed for nearly four years. The flaw could have allowed the creation of untraceable counterfeit ZEC coins. Fortunately, with assistance from Anthropic’s Claude Opus 4.8 model, Hornby identified this flaw before any exploitation could occur. Between June 2 and June 4, the Zcash network implemented an emergency upgrade that included both a soft and hard fork.
On June 5, Wilcox disclosed the vulnerability publicly, leading to a drastic drop in ZEC's price—between 30% and 50%—wiping out billions in market capitalization. Given Zcash's privacy-centric design, it is exceedingly difficult to verify whether counterfeit coins were minted during the vulnerable period.
What does this new audit mean for Zcash's future? Wilcox's announcement about the audit indicates a commitment to enhancing the security framework of Zcash. The integration of AI-assisted code reviews into Zcash's security practices follows the identification of the Orchard vulnerability. This collaborative effort with Anthropic aims to continue utilizing AI for bug detection in the future.
The implications of the Orchard vulnerability extend beyond Zcash itself. It exposes the inherent conflict within privacy coin architecture. Unlike audit-friendly blockchains such as Bitcoin or Ethereum, Zcash's shielded pools remain opaque, making it impossible to conduct a full verification of historical supply inflation once a soundness bug emerges. As this situation illustrates, the challenges facing privacy coins also apply to smart contract security throughout the blockchain industry. The ongoing partnership between Shielded Labs and AI auditing is a positive step forward for improving security safeguards, ensuring that future vulnerabilities can be caught before posing a significant threat.