According to Josh Swihart, founder of Zcash Open Development Lab (ZODL), the Zcash team deployed a two-step emergency upgrade on Sunday to resolve a critical vulnerability in the Orchard shielded pool that allowed unlimited counterfeiting of ZEC. A soft fork initially disabled Orchard transactions, followed by a hard fork (NU6.2) activated on June 3 to re-enable the transactions after fixing the underlying issue. Shielded Labs confirmed the bug was fixed with no evidence of actual exploitation.
ZEC rebounded 42% from a June 5 low of $303, trading at $428.67 as of report time, according to The Block, after the vulnerability disclosure sparked a more than 50% selloff from around $630.