Zcash emergency upgrade fixes Orchard bug; ZEC steadies

On June 3 the Zcash Foundation issued emergency Zebra 4.5.3 and 5.0.0 to address a soundness bug in the Orchard shielded pool. Zebra 4.5.3 disabled Orchard actions with an emergency soft fork at block height 3,363,426. Zebra 5.0.0 activated the NU6.2 hard fork at block 3,364,600 to re-enable Orchard with a corrected circuit. No funds were reported lost and the total supply of ZEC remained unchanged.

The flaw was in the Orchard Action circuit, the zero-knowledge component that processes Orchard transactions. If exploited, the flaw could have allowed value to be created without detection. The Foundation reported the issue was fixed before any known exploitation. Transparent and Sapling transactions continued to function during the upgrade window.

The Foundation posted on X: “Zebra 5.0.0 is out — all node operators should upgrade now. NU6.2 activated, re-enabling Orchard with a corrected circuit. Total ZEC supply confirmed intact throughout.”

Several network explorers briefly appeared to show block production stalled near height 3,364,601 while nodes and indexers resynchronized to the updated consensus rules. Mining pools continued to produce blocks under the new rules and most explorers had caught up by midday on June 3.

Market data showed ZEC trading around $596 at the time of reporting, up more than 5% over 24 hours and ranging roughly between $560 and $638 on the day. ZEC’s market capitalization was near $9.9 billion, placing the token around the 13th largest by that measure.

The Foundation urged all node operators to upgrade to Zebra 5.0.0 to complete the network transition to the corrected consensus rules. Market observers noted ongoing interest in privacy-focused assets and occasional discussion of potential ETF applications for ZEC, though no formal listings have been announced.