Zcash is getting an upgrade tomorrow called Ironwood, activating around 8 a.m. Eastern time at block height 3,428,143. This update, also known as NU6.3, introduces a new privacy feature and moves funds from the older Orchard system to a more modern one using a public record of balances.
This change comes after a serious security issue was found in Orchard in late May. This flaw potentially let someone create an endless number of fake Zcash (ZEC) coins without being noticed. The problem existed within the code since Orchard’s release in 2022.
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A quick software update, NU6.2, fixed the security flaw in early June. Since Orchard transactions keep financial details and user identities private, researchers haven’t been able to determine if anyone took advantage of the vulnerability before the update was released.
Despite thorough investigations by core developer Sean Bowe and teams from Shielded Labs and the Zcash Open Development Lab finding no proof of counterfeit coins, concerns about this possibility persisted.
New pool and turnstile close the gap
On July 10th, the Zcash Foundation announced that the upcoming Ironwood upgrade will utilize the same technology as the existing Orchard system but operate with a completely separate network. After the upgrade is activated, all new private transactions will automatically be processed using Ironwood. The original Orchard network will no longer accept any new funds or transfers within it.
Any leftover funds can only be withdrawn using the current system, which keeps a public record of every transaction – both incoming and outgoing. This ensures that no more ZEC can be taken out of the original fund than was originally put in.
Eventually, this update will allow node operators to easily and reliably verify that the total number of tokens in circulation hasn’t been increased without authorization.
This update includes a new feature called quantum-recoverable notes. This means even if future quantum computers were to compromise current security systems, Ironwood funds could still be recovered. While this isn’t complete protection against quantum computer attacks – more comprehensive updates are planned for the future – it’s an important step forward. Older versions of the system don’t have this recovery option.
Once the update is active, those running nodes need to use software that works with the new rules before block height 3,428,143. If they don’t, their node could end up on a separate, smaller network. Zebra version 6.0.0 already has everything needed to support the changes.
Most wallets will ask users with Orchard holdings to easily move their funds in one step. Some exchanges and services might temporarily stop deposits and withdrawals as they verify their systems are ready for the change.
As of Monday morning, the network was still over 1,500 blocks away from its goal. Based on typical block creation times, it’s expected to reach that goal around mid-afternoon UTC on July 28th. Currently, about 3.76 million ZEC are held in Orchard, ready to be released when the network activates.
2026-07-27 15:03