Zcash (ZEC) Price: $3 Billion Wiped Out After a Hidden Bug Sat Undetected for Four Years

TLDR

• Zcash (ZEC) dropped around 40% after disclosing a critical security bug in its Orchard shielded pool
• The vulnerability was a “soundness” flaw in the zero-knowledge proof circuit, potentially present since 2022
• Security researcher Taylor Hornby found the bug using Anthropic’s Claude Opus 4.8 AI
• No confirmed exploitation was found, and the network’s turnstile mechanism prevented unauthorized supply expansion
• Zcash deployed an emergency soft fork and a permanent hard fork (NU6.2) within days to fix the issue

Zcash (ZEC) fell roughly 40% in early June 2026 after the network disclosed and patched a serious security flaw in its Orchard shielded pool. The crash erased more than $3 billion from ZEC’s market capitalization and pushed the price below $350.

The vulnerability was described as a “soundness” flaw in Zcash’s zero-knowledge proof circuit. It may have existed since the Orchard pool launched in May 2022, and had gone undetected through multiple security audits.

Security researcher Taylor Hornby found the bug on May 29, 2026, while conducting research commissioned by Shielded Labs. The discovery was made using Anthropic’s Claude Opus 4.8 AI alongside a custom analysis suite.

Hornby and the AI developed a working proof-of-concept that could generate counterfeit ZEC in a local test environment. However, the network’s internal turnstile controls prevented any unlimited supply inflation in practice.

How the Fix Was Deployed

Zcash’s development ecosystem moved quickly. An emergency soft fork was deployed via Zebra 4.5.3 on June 2, temporarily suspending Orchard transactions to remove the attack path.

The permanent fix came on June 3 through the NU6.2 hard fork, activated at block 3,364,600. This introduced a revised circuit and a new verifying key. Orchard functionality was then restored.

On June 4, Zcash co-founder Zooko Wilcox, along with Jason McGee and Taylor Hornby, released a full public explanation of the incident. They stated there was no known exploitation and that the total ZEC supply remained intact.

Crypto analyst Ardi (@ArdiNSC) shared his read on the price action after the crash. He noted that ZEC gave back nearly an entire multi-month rally — a move of almost 250% — in just a few days. He expects a brief relief rally into the $430–$480 range, followed by another leg down if that level fails to hold as support. He said he would only change his view if ZEC sees consecutive closes above $520.

Market Reaction and Uncertainty

ZEC had briefly traded above $600 before sentiment shifted once the vulnerability details went public. The drop below $350 followed reports that investor Arthur Hayes had liquidated his ZEC position.

A key concern among traders was that Zcash’s privacy design makes it impossible to fully verify whether the bug had been exploited before discovery. Unlike Bitcoin, the shielded pool’s internal movements are not publicly visible.

Shielded Labs outlined plans for continued AI-assisted security research, a formal verification project for the Orchard circuit, and a possible new shielded pool with improved supply verification tools.

Cameron Winklevoss described the incident as a sign of the project’s strength, saying elite researchers are constantly testing and hardening the network.

As of the latest reports, no exploitation has been confirmed, the NU6.2 upgrade is live, and the ZEC price remains below $400.

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