Zcash fixes Orchard bug after emergency network upgrade

Written by Ezra Reguerra , Staff Writer.Reviewed by Bryan O'Shea , Staff Editor.Written by Ezra Reguerra , Staff Writer.Reviewed by Bryan O'Shea , Staff Editor.Zcash fixes Orchard bug after emergency network upgradeLatest NewsPublishedJun 3, 2026Zcash Open Development Lab said the network briefly became unstable as miners upgraded, while the Zcash Foundation said there was no evidence of an exploit.Zcash developers temporarily suspended Orchard transactions after discovering a critical vulnerability in the privacy-focused blockchain’s latest shielded pool, then restored functionality through an emergency network upgrade.On Wednesday, the Zcash Foundation said the vulnerability affected Orchard’s zero-knowledge proof circuit and could have allowed invalid state transitions within the pool. However, the Foundation said there was no evidence that the bug was exploited, no unauthorized value creation was detected, and user privacy was not affected.The fix was carried out through a two-step emergency upgrade. Zebra 4.5.3 temporarily disabled Orchard actions, while Zebra 5.0.0 activated the NU6.2 upgrade to re-enable Orchard with a corrected circuit, according to the Foundation. The emergency response shows how a bug in core privacy infrastructure can require coordinated action across miners, exchanges and node operators, even when user funds and total supply are not affected.The upgrade also appeared to have caused confusion across parts of the Zcash ecosystem. One Zcash block explorer showed block 3,364,601 as the latest block mined at 5:27 am UTC, while the page listed it as mined about four hours earlier, prompting reports on X that the Zcash network was down. Zcash Open Development Lab (ZODL)-affiliated contributor Tatyana said the network experienced “a brief period of instability” as miners upgraded and converged on new consensus rules. The post did not directly name the block explorer or wallet issues, but said network stability had been fully restored by a…

Zcash fixes Orchard bug after emergency network upgrade

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