Zcash Sets Ironwood Network Upgrade for July 28 Activation

Upgrade Details and Timeline

Zcash core developer Sean Bowe announced that the Ironwood upgrade, known as NU6.3, will activate at block height 3,428,143, expected around 8 AM EST on July 28. Major organizations in the ecosystem have committed to this date.

The upgrade follows the discovery of an "infinity" bug in the Orchard shielded pool earlier in the year. Ironwood replaces the existing pool with a new one and implements measures to verify supply integrity during the transition.

Addressing the Orchard Vulnerability

Ironwood closes the current Orchard pool to new activity. Funds moving out must pass through an accounting checkpoint before entering the new shielded pool. This process is intended to check for any potential issues stemming from the earlier bug.

Developers have stated that no evidence exists of the vulnerability being exploited to create counterfeit tokens. The checkpoint mechanism during migration serves as an additional layer of verification for the circulating supply.

Ecosystem Preparation and Infrastructure Changes

The decision to proceed on July 28 came after requests for more preparation time from exchanges, mining pools, wallets, and other participants. This delay allows for smoother transitions, including moves to updated software stacks like Zebra and related tools.

Testnet activities and audits have supported the rollout. Independent reviews, including work involving Anthropic's Mythos AI, reported no additional serious issues in the codebase.

Supply Milestone Coincides with Upgrade

Zcash recently reached a significant point with its token supply. Circulating supply has now exceeded 16.8 million ZEC, representing more than 80% of the maximum 21 million total.

This development occurs alongside the technical upgrade, drawing attention to the network's fixed supply model and ongoing efforts to maintain its integrity.

Market Context Following Recent Events

Following the public disclosure of the Orchard issue in early June, ZEC experienced a substantial price movement, dropping from around $602 to $299 before recovering toward the $490-$500 range in subsequent weeks.

The Ironwood activation represents a key step in the network's response to that event, aiming to strengthen the shielded transaction system that forms a core part of Zcash's design.