Zcash activated the Ironwood (NU6.3) network upgrade at block 3,428,143 on July 28. It seals the Orchard shielded pool, which contained 3.66 million ZEC, and introduces a new privacy pool with formal verification and independent security audits.
• The upgrade responds to a critical soundness vulnerability discovered in May.
• It also adds a “turnstile” mechanism that caps pool withdrawals at verified deposits.
Matters because: it strengthens Zcash’s supply integrity verification and improves protection against future soundness issues while preserving privacy.