Firo is hours from a hard fork (network rule-changing upgrade) designed to fix an August vulnerability in Spark (private transaction protocol), its system for private transfers. The chain was at block 1,370,847 at 1:45:47 a.m. UTC on Sept. 4, leaving 153 blocks before activation, which Firo estimated would occur around 10 a.m. UTC. The block height, rather than the clock, controls the change. Users and operators must upgrade to v0.14.18.0, while older nodes will become incompatible after the threshold. The flaw affected multi-input Spark spends and could, under specific conditions, permit forged coins and supply inflation, though Firo said wallets, keys, address balances and single-input spending were not compromised. The release adds a versioned Chaum V2 proof and transaction format, restores normal multi-input spending and keeps historical transaction validation. Existing funds do not need to be migrated or reminted, and Firo plans a technical disclosure and post-mortem after activation.