Zcash will activate its Ironwood network upgrade on July 28, addressing an “infinity” bug discovered in May in the blockchain’s private transaction pool, Orchard. The upgrade was announced in June and will take place at block height 3,428,143, roughly 8:00 AM EST, according to core developer Sean Bowe. Major Zcash organizations have committed to the activation.
Ironwood closes the existing Orchard pool, prevents any new activity in it, and opens a new private pool. Funds leaving Orchard must pass through an accounting checkpoint before entering the new pool, a step designed to create a traceable record that could show whether counterfeit Zcash (ZEC) tokens were ever produced as a result of the Orchard bug.
Shielded Labs had warned publicly that exchanges, mining pools, wallets and other infrastructure participants might need more time to prepare and had suggested delaying Ironwood. The confirmed activation date is one week later than an earlier target of July 21.
Shielded Labs and other developers have said the migration process itself may reveal whether the vulnerability was exploited: a hypothetical counterfeiter would have to decide to move suspicious funds and risk exposing them, or leave the funds behind and risk being unable to move them later.
The Orchard bug’s disclosure on June 3 caused the price of ZEC to fall sharply—about 50% from $602.68 to $299.25. The price has partially recovered since then and was trading around $492.61 at the time of reporting. Separately, Zcash has surpassed a supply milestone: more than 80% of its 21 million ZEC maximum has now been issued, with roughly 16,806,723 ZEC in circulation.
Independent reviews including audits have been carried out since the bug was found; some reports indicated no additional serious issues. The Ironwood upgrade is intended to both patch the vulnerability and provide a controlled path forward for shielded transactions and ecosystem participants.
