Firo Hard Fork Patches Spark Vulnerability at Block 1,371,000
Firo activates v0.14.18.0 to fix a multi-input Spark spend flaw disclosed in August that risked supply inflation. Upgrade required before block 1,371,000.
Firo will activate a mandatory hard fork at block 1,371,000, expected around 10 a.m. UTC on September 4. The chain stood at block 1,370,847 as of 1:45 a.m. UTC.
The upgrade installs a new Chaum V2 proof and transaction format that restores multi-input Spark private spends. A temporary restriction to single-input spends, introduced in v0.14.17.2, ends at the fork.
Upgrade requirements and remaining unknowns
The project disclosed the vulnerability on August 13. Under specific conditions the flaw allowed forged coins in multi-input Spark transactions, though it did not expose keys or affect single-input spends. A controlled test by the researcher produced roughly 200 FIRO; the project reported no other evidence of inflation at the time of disclosure.
Wallets, nodes, masternodes, miners, and exchanges must run v0.14.18.0 after the fork. Historical Spark transactions stay valid and no migration or reminting is required. The exact number of nodes and exchanges still on pre-fork software remains unknown. A full technical disclosure and post-mortem are scheduled after activation.