CryptoSlate
Zcash became the rare green ticker in a brutal session for digital assets after a brief outage scare turned out to mask one of the most ambitious network upgrades in the chain's history. ZEC traded near $620 and touched an intraday high above $642, up roughly 10% on the session, while Bitcoin slid to around $65,900 and Ethereum fell to roughly $1,832 — both down more than 4%, according to CryptoSlate data.
The episode began after Zcash completed an emergency response to a soundness vulnerability in Orchard, the shielded pool that underpins the network's most advanced privacy transactions and was introduced with the NU5 upgrade in 2022. Block explorers went stale during the upgrade, fueling rumors that the chain had halted; in reality, miners kept producing blocks and ZODL founder Josh Swihart wrote on X that "Zcash was never down. Many block explorers have been using unpatched nodes. Happens with every network update."
Why it matters
The flaw was discovered May 29 by independent researcher Taylor Hornid, working on protocol security research for Shielded Labs, and confirmed by ZODL engineers within hours. The vulnerability sat inside the Orchard zero‑knowledge proof circuit — a soundness bug means the system could accept something it should reject, in this case potentially allowing double‑spends inside the Orchard pool. Crucially, the Foundation said the 21 million ZEC supply cap remained intact via the network's turnstile mechanism, and Sapling and transparent transactions kept operating while Orchard was suspended.
The fix required two coordinated steps. A soft fork at block height 3,363,426 around 02:00 UTC on June 2 temporarily rejected Orchard‑containing transactions and blocks, buying time to develop a permanent patch without publicly disclosing exploit details. The NU6.2 hard fork then activated at block height 3,364,600 early Wednesday, re‑enabling Orchard with a corrected circuit and requiring node operators to upgrade to Zebra 5.0.0. The Foundation called it only the second security‑driven protocol upgrade in Zcash's history since launch in 2016.
Frequently asked questions
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Did Zcash actually go offline during the outage scare?
No. Block explorers went stale during the emergency response to an Orchard soundness vulnerability, fueling the rumor, but miners kept producing blocks and transactions kept confirming. ZODL founder Josh Swihart said on X that "Zcash was never down" — many explorers were still running unpatched nodes.
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What was the Orchard vulnerability and how serious was it?
The flaw sat inside Orchard's zero-knowledge proof circuit — a soundness bug that, in theory, could have allowed double-spends inside the shielded pool. The Zcash Foundation said the 21 million ZEC supply cap remained intact via the network's turnstile mechanism, and that user privacy was never affected.
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What did the NU6.2 hard fork actually change?
NU6.2 activated at block height 3,364,600 and re-enabled Orchard using a corrected zero-knowledge circuit, fixing the soundness vulnerability. It followed an earlier emergency soft fork that had temporarily rejected Orchard-containing transactions. Node operators were urged to upgrade to Zebra 5.0.0.
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Why did ZEC rally while Bitcoin and Ethereum fell?
ZEC rose about 10% on the session to near $620, while BTC slipped to around $65,900 and ETH to around $1,832 — both down more than 4%, with over $1B in leveraged crypto longs liquidated. Traders appeared to price the coordinated flaw-to-fix response as resilience rather than impairment, against a broader risk-off…
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Is Orchard the same as Zcash's original shielded pools?
No. Orchard is Zcash's newest shielded pool, introduced with the NU5 upgrade in 2022, and uses Halo 2 — which does not require a trusted setup, a long-running concern in privacy-coin design. Sapling and transparent transactions continued operating normally while Orchard was temporarily suspended.
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