Zcash fixes Orchard bug after emergency network upgrade

Zcash 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. 

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