Zcash (ZEC) has been under heavy pressure since a critical vulnerability was discovered in its Orchard shielded pool. On May 29, security engineer Taylor Hornby, hired by Shielded Labs, found an under-constraint flaw in the Orchard circuit that allowed an attacker to input arbitrary values into elliptic curve multiplication while still passing verification — theoretically enabling unlimited undetectable ZEC minting. The bug had existed since Orchard launched in May 2022, lying dormant for over four years. An emergency network upgrade patched it on June 2, 2026, and founder Zooko Wilcox said exploitation was "extremely unlikely." But community confidence suffered a severe blow.
Ironwood: Giving Verification Back to Users
On June 6, Zooko published the Ironwood proposal, aiming to let every Zcash user independently verify that the total ZEC supply is correct — without trusting anyone. Ironwood does three things: 1) Opens a new shielded pool using the same Orchard circuit, but with the recent forging flaw fixed; 2) Lock new outputs in the old Orchard pool — any transaction attempting to create a new output there is rejected; 3) Adds higher assurance to the code through AI-assisted security audit and formal verification to eliminate other potential forging bugs.
Turnstile Mechanism: Instant Supply Integrity
Once Ironwood activates, ZEC in the old Orchard pool can only exit via the turnstile, an on-chain mechanism that tracks how much enters and leaves each pool, rejecting any withdrawal exceeding the legitimate inflow. This means users do not need to wait for Orchard funds to migrate — from the moment Ironwood starts, consensus rules directly prove that no more ZEC can be in circulation than the correct amount. Excess ZEC cannot secretly circulate within Orchard Pool or escape to other pools.
Was the Vulnerability Exploited?
Ironwood may also reveal whether the bug was exploited. When legitimate users move funds out of the old pool, if a forger exists, they face a dilemma: attempt to move counterfeit ZEC (risking exposure) or leave it behind (forever stuck). Outcome A: No excess ZEC tries to leave — strong evidence the bug was never exploited. Outcome B: Excess ZEC is blocked and effectively destroyed — creating a public, verifiable proof of forgery. The team believes Outcome A is far more likely.
Impact on Wallets and Users
All wallets supporting the current Orchard pool are encouraged to also support the new pool. After activation, migrating funds from the old to the new pool will reveal transfer amounts and timing, but the privacy impact is considered limited and can be mitigated. Old Orchard receivers remain valid; any ZEC sent to them after Ironwood activates will automatically be credited in the new pool.
Timeline and Uncertainty
Like most network upgrades, Ironwood requires development, testing, review, and ecosystem coordination. Shielded Labs warns that such work usually takes longer than expected — better to under-promise than over-commit. An extra variable is the ongoing deprecation of zcashd; exchanges, mining pools, wallets, and infrastructure providers must migrate to the Zebra client, and their progress will affect the upgrade schedule. Clear timelines will emerge as the implementation plan matures.
Coda: The team emphasizes that users should not be forced to trust anyone's judgment about Zcash supply integrity. Ironwood's purpose is to make that integrity something anyone can verify for themselves.