Zcash Activates Ironwood Upgrade — $1.7B Orchard Pool Closed, Coins Pass Through ‘Turnstile’

Yesterday, Zcash underwent an upgrade designed to close the Orchard pool vulnerability. We break down how it went and what users need to know. On July 28, 2026, the Ironwood upgrade was activated on the Zcash mainnet at block 3,428,143.

Developers launched a new private transaction pool to replace Orchard, where a critical vulnerability was discovered in late May. At activation, Orchard held about 3.66 million Zcash (ZEC) tokens.

Hot topic: Zcash Launches Ironwood Upgrade — ZEC Recovers to $500 After 50% Drop The new Ironwood pool started with a zero balance. All funds from the old pool must be moved by their owners through a “turnstile” mechanism that limits withdrawals to the verifiable deposit amount.

https://t.co/N3GWdyQipM— Zcash Open Development Lab (@zodl_co) July 28, 2026 How Ironwood Fixes the Orchard Vulnerability: ‘Turnstile‘ and Formal Verification The Orchard bug was discovered on May 29 by Shielded Labs security engineer Taylor Hornby while analyzing code with Anthropic’s Claude Opus 4.8.