Zcash has confirmed that its Ironwood network upgrade will activate on July 28, replacing the Orchard shielded pool after a critical vulnerability was disclosed. The upgrade is designed to close the Orchard pool and introduce an accounting checkpoint that could reveal whether counterfeit ZEC was ever created through the bug.
Ironwood activation details
Zcash core developer Sean Bowe announced on Thursday that Ironwood will activate at block height 3,428,143, expected around 8 a.m. EST on July 28. This represents a one-week delay from the originally planned July 21 rollout, following concerns from Shielded Labs that exchanges, mining pools, and wallet providers might need more time to prepare. Many of these entities were also replacing Zcash's long-running zcashd software with the new Z3 stack, which includes Zebra, Zaino, and Zallet.
Addressing the Orchard vulnerability
Ironwood was proposed after developers disclosed an “infinity” bug in Zcash’s Orchard shielded pool, the network’s primary privacy-focused transaction system. Shielded Labs said the flaw could theoretically have allowed an attacker to create unlimited counterfeit ZEC, although it found no evidence that the vulnerability had been exploited. Emergency updates addressed the software flaw before it became public, first disabling Orchard transactions through a temporary network update, then activating the NU6.2 hard fork on June 3 to fix the underlying issue and restore the pool.
Once Ironwood goes live, the existing Orchard pool will stop accepting new activity, and users will instead move funds into a newly created private pool. According to Shielded Labs, coins leaving Orchard must pass through an accounting checkpoint before entering Ironwood, creating a process that could reveal evidence if any counterfeit ZEC had been created through the earlier bug. The organization said users migrating funds effectively force any hypothetical counterfeiter to either move fake coins and risk exposing them or leave those coins behind without a future way to transfer them.
ZEC price recovery and supply milestone
Following public disclosure of the Orchard vulnerability on June 3, ZEC fell about 50% from $602.68 to $299.25. The token has since recovered part of those losses and was trading at $492.61 at the time of writing. Separately, Zcash passed another network milestone this week: a post from ruZCASH on Monday showed the circulating supply had reached 16,806,723 ZEC, meaning more than 80% of the cryptocurrency’s maximum 21 million supply has now been issued.