Zcash completes NU6.2 hard fork to fix Orchard pool vulnerability

The Zcash (ZEC) Foundation officially announced that independent security researcher TaylorHornby discovered on May 29 that Zcash's Orchard zero-knowledge proof circuit contained a serious reliability vulnerability that could allow the Orchard pool to double spend. ZODL core engineers confirmed the problem within a few hours and started the repair. In order to buy time, the Orchard operation was temporarily disabled in the early morning of June 2 through the Zebra 4.5.3 emergency soft fork. Finally, the NU6.2 hard fork was activated through Zebra 5.0 today. At 12:05 noon Beijing time, the main network successfully completed the upgrade at a block height of 3,364,600. Orchard was re-enabled with the corrected circuit, and the vulnerability was permanently closed. This is the second time that Zcash has triggered an protocol upgrade due to security issues since it was launched in 2016. No known utilization occurred throughout the entire process. The network total guard mechanism confirms that the total supply is always complete, and user privacy, Sapling and transparent transactions have not been affected.