Zcash Ironwood Upgrade Is Now Live, Here’s All You Need to Know

The Zcash network has launched its Ironwood upgrade at block 3,428,143 on Tuesday. Ironwood introduces a new shielded Zcash pool while closing the previous Orchard pool.

Developers said this update would strengthen the network after researchers found a security flaw earlier this year. There was no evidence the bug was ever used. But the new upgrade aims to remove doubts about the network’s supply and security.

Zcash launches Ironwood with stronger security

According to an X post by the team’s development lab, Ironwood, also known as NU6.3, is now live, replacing the Orchard shielded pool. The old pool still holds about 3.66 million ZEC, worth $1.7 billion.

Ironwood started out with zero ZEC tokens in the pool. Every user must move their assets from Orchard into the new pool.

Shielded pools help hide transaction amounts and user identities through zero-knowledge proofs. This allows transactions to be verified without sharing information.

The upgrade comes after Shielded Labs researcher Taylor Hornby noticed a flaw in Orchard’s proof circuit back in May. This bug could have allowed someone to create fake ZEC coins without leaving any visible record on the blockchain. The flaw had been there since Orchard launched in May 2022.

Meanwhile, researchers confirmed that there was no evidence that anyone ever used the vulnerability. It was reported that if counterfeit coins had been created, the most likely next step would have been selling them. 

That would have required coins to leave the shielded pool. Orchard’s balance grew during the time the bug existed. This suggests it had no abnormal shift in supply.

Developers patched the flaw immediately it was highlighted. However, because shielded transactions are private by design, they could never prove that fake coins were never created. The team then introduced the Ironwood upgrade to address this issue.

Dev team introduces a new accounting system

The major feature of Ironwood is a new accounting rule called the turnstile. This system allows users to move funds out of Orchard. It also limits withdrawals to the exact amount that was deposited into the older pool.

In simple terms, if counterfeit coins were somehow created, they would remain trapped in Orchard and never enter the new shielded pool. Developers say this protects the integrity of the network while allowing users to migrate at their own pace.

“First, the Orchard pool is now restricted. New value can no longer enter Orchard, and funds already inside the pool must pass through the turnstile to exit. They can no longer circulate freely within the pool.”

According to the migration tracker, about 160,109 ZEC have been moved into Ironwood.

Source: Ironwood Migration Tracker

The migration is completely voluntary. This means users can decide when they want to transfer their funds.

Ironwood prepares Zcash for future technology

The new update also included a ZIP 2005 update that adds quantum-recoverable notes. This feature was made to protect users’ funds when quantum computers become powerful enough to weaken today’s encryption systems.

Developers said that this does not make the network fully quantum-safe today. But it helps lay a foundation that would allow users to recover their funds when new recovery tools are launched in the future.

Another major improvement in the update is formal verification. Project Tachyon shared that researchers have completed a machine-checked mathematical proof that would cover Ironwood’s balance integrity. 

Formal verification mathematically helps prove that critical parts of the code would behave correctly under their intended rules.

Zcash co-founder Sean Bowe lauded the efforts of the development team on the new upgrade.

Soundness of our zk-SNARK would have been great on its own. But a cross-team collaboration has just changed Zcash’s history forever, eliminating all sources of undetectable counterfeiting bugs from the new Ironwood protocol. https://t.co/BUciBdzUJV

— Sean Bowe (@ebfull) July 28, 2026