Zcash Ironwood Upgrade Nears as Developers Work to Restore Confidence After ZEC Crash

In a series of posts on the Zcash forum on Thursday, developers said the privacy-focused cryptocurrency’s Ironwood upgrade is moving closer to activation—first on a testnet—bringing the network a step nearer to allowing users to verify the integrity of its circulating supply following last month’s disclosure of a critical counterfeiting vulnerability.

Announced in June, Ironwood is a proposed Zcash network upgrade that introduces a new shielded pool and accounting system designed to let anyone verify the network’s circulating supply while preserving transaction privacy.

The upgrade is intended to eliminate the uncertainty exposed by the Orchard vulnerability in May, which left developers unable to prove whether counterfeit ZEC had ever been created.

The panic around the vulnerability disclosure led to a massive price drop for the coin, which lost more than half of its value in a matter of two days, falling from more than $600 to a recent bottom around $300. ZEC has made up about half the losses so far, recently trading at $457, per data from CoinGecko.

“At Shielded Labs our focus has been security, and in particular our new project, which we are calling Zero, of supporting enterprise users (e.g. mining pools, exchanges, and wallets),” Zcash co-founder Zooko Wilcox wrote. “Our current focus within the Zero project is to help them prepare to safely make the transition to Ironwood.”

The update comes weeks after security researcher Taylor Hornby, using Anthropic’s Claude Opus 4.8, uncovered a four-year-old flaw in Zcash’s Orchard shielded pool that could have allowed unlimited counterfeit ZEC to be created without detection.

Although developers patched the bug on June 1, Zcash’s privacy features meant there was no cryptographic way to determine whether it had ever been exploited, which led Zcash developers to propose Ironwood to eliminate that uncertainty.

Since then, Zcash developers say they have made significant progress on Ironwood activation in Zcash.

“Ironwood’s prompt and safe activation on Zcash mainnet is extremely important to our users, in addition to the formal verification work we’re doing in parallel to provide reassurance that there aren’t any supply integrity concerns,” Zcash developer Sean Bowe wrote on X on Thursday, adding that “sufficient hash rate is signaling technical readiness for the mainnet upgrade.”

“The outstanding concern is that some wallets will not be prepared for the upgrade in time,” Bowe wrote. “This does not justify delaying Ironwood, given there will be adequate alternatives and sufficient time on testnet for anyone who needs it.”

Jason McGee of Shielded Labs said development is focused on two parallel efforts: the Ironwood (NU6.3) network upgrade, and migrating the Zcash ecosystem from its legacy Zcashd software to the new Z3 stack, which includes the Zebra full node, the Zaino indexing service, and the Zallet wallet.

According to McGee, development is moving forward on schedule, and testnet activation of the new consensus rules “is expected shortly.”

“The current goal is to complete both efforts by late July,” McGee wrote. “With regard to Ironwood, the teams at Project Tachyon, Valar Group, ZODL, the Zcash Foundation, and Shielded Labs have been working hard and have made significant progress over the past several weeks.”

Work is also continuing on formal verification of the new circuit, McGee added, with the goal of completing a proof of soundness before Ironwood activates.

The larger challenge, McGee said, is preparing infrastructure providers for the transition to the new software stack. Key Z3 components, including Zallet and Zaino, are still under development, leaving exchanges, mining pools, and wallet providers with limited time to deploy and test everything before Ironwood activates.

“The consistent feedback we’ve received is that completing both the Ironwood upgrade and the migration to Z3 on the current timeline will be challenging,” McGee wrote, adding that a recent questionnaire had some respondents “indicating they’ll be ready while others said they need additional time.”

According to McGee, several options are being considered to reduce deployment risk, including delaying Ironwood, conducting independent third-party security audits before deployment, or temporarily supporting Ironwood through Zcashd while partners complete the migration.

“Ultimately, we all share the same goal to activate Ironwood as quickly as possible while making sure our partners can safely migrate away from Zcashd,” he wrote. “We think the focus over the coming weeks should be on making that transition as smooth and secure as possible.”