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Zcash sets NU6.3 activation at block 3,428,143 after Orchard pool flaw

Zcash sets NU6.3 activation at block 3,428,143 after Orchard pool flaw

Ironwood is scheduled for July 28 to address the Orchard vulnerability, close the affected pool and shift Zcash full-node software to Zebra.

ZEC

Fact Check
The primary source (Sean Bowe / @ebfull tweet) directly confirms the Ironwood NU6.3 mainnet activation at block height 3428143 with all major organizations committed, matching the claim exactly. Odaily and BlockBeats both attribute the '20:00 Beijing time July 28' activation to Sean Bowe and describe the Orchard pool flaw enabling unlimited counterfeit ZEC minting. The only minor inconsistency is the time: Bowe's tweet says 8AM EST which converts to ~21:00 Beijing time (UTC+8), whereas the claim and Chinese-language reports state 20:00 Beijing. This ~1hr conversion discrepancy is minor and does not affect the substance. All core facts—block height, upgrade name, major-orgs commitment, and the counterfeit-ZEC Orchard vulnerability—are fully corroborated.
Summary

Zcash is set to carry out its Ironwood upgrade on July 28 after developers proposed the change in response to a critical vulnerability discovered in May in the Orchard private transaction pool. The NU6.3 upgrade is designed to shut the compromised Orchard pool, prevent new activity there and launch a new shielded pool, while funds leaving Orchard will have to pass through an accounting checkpoint that may help show whether the bug disclosed on June 3 was ever used to create counterfeit ZEC. Pacu, developer support lead at Zcash Open Development Lab, said the upgrade is scheduled for July 28, while earlier updates had fixed activation at block 3,428,143, around 8 a.m. EST that day. The upgrade will also migrate Zcash full-node software to Zebra. Sean Bowe had said the activation would proceed a week later than the earlier July 21 target despite concerns from Shielded Labs that exchanges, mining pools and wallets might not have enough time to prepare. ZEC fell 50% to $299.25 from $602.68 after the flaw was disclosed and was trading at $492.61 at the time of writing. Zcash has also passed 80% of its maximum 21 million token supply, with ruZCASH saying 16,806,723 ZEC are in circulation.

Terms & Concepts
  • Orchard pool: Zcash’s private transaction pool that is being closed after a vulnerability was discovered.
  • Zebra: The full-node software that Zcash plans to migrate to as part of the Ironwood upgrade.
  • accounting checkpoint: A control in the migration process that checks funds moving from the old pool to the new one.