Zcash Rolls Out Its Biggest Network Upgrade to Fix Orchard Privacy Pool Flaw

Zcash has completed its largest network upgrade after the Zcash Foundation disclosed a critical vulnerability in the Orchard privacy pool circuit that could, in theory, have enabled double-spending. The issue was discovered on May 29 by security researcher Taylor Hornby, Decrypt reported, citing the Foundation. Zcash Open Development Lab and the Foundation executed a two-step emergency response within five days. The first step was an emergency soft fork that temporarily froze all Orchard transactions. The second was a hard fork upgrade, NU6.2, which repaired the zero-knowledge proof verification key and restored normal operation. The team said the built-in "turnstile" mechanism showed no evidence of inflation or an active attack. Block production continued normally on-chain, though some block explorers briefly failed to read the chain while nodes were upgrading. Zcash urged node operators to upgrade immediately to Zebra 5.0. ZEC was trading around $629, up more than 10% over the past 24 hours and over 53% in the past 30 days.