Privacy coin flaw risks endless token creation, leaving node operators with a deadline in hours to fix it

The Firo hard fork was 153 blocks away from activation early Friday, leaving wallet users and network operators only hours to install software that repairs an August vulnerability in the privacy coin’s Spark transaction system.The chain reached block 1,370,847 at 1:45:47 a.m. UTC on Sept. 4. The fork activates at block 1,371,000, which Firo estimated would arrive around 10 a.m. UTC. The block height, not the clock, determines when the new rules begin.Firo said wallet users, full-node and masternode operators, miners, exchanges and other service providers should upgrade to v0.14.18.0 before activation. Nodes left on older software will no longer be compatible with the upgraded network after the threshold.What the Firo hard fork repairsSpark is Firo’s protocol for private transactions. The project disclosed on Aug. 13 that a flaw in multi-input Spark spends could, under specific conditions, allow forged coins and inflate supply. Firo said the issue did not compromise wallets or keys, let an attacker remove coins from an address, or affect single-input spends.The researcher who disclosed the flaw generated about 200 FIRO on mainnet in a controlled test. Firo said it had found no evide...