Attacker Mints 4 Billion Harmony ONE Tokens and the Network Weighs a Rollback

Harmony, a proof-of-stake layer-1 network, confirmed on Tuesday that an attacker created roughly 4 billion ONE tokens it never authorized. The new tokens amount to about 26 percent of the supply that existed before the incident, according to on-chain researchers cited by crypto news channels. The token fell sharply on the day, with Decrypt reporting a 37 percent decline and CoinDesk reporting a fall of at least 26 percent as trading volume surged.

Two separate failures made the incident possible. The first was the issuance path itself, which allowed minting without valid authorization. Harmony has not yet published a full root-cause report, and early accounts from independent analysts point to token creation carried out through empty blocks. The second failure was informational. The network's total-supply reporting did not immediately reflect the new tokens, so the dashboards that exchanges and market makers normally watch showed nothing unusual while the attacker moved funds. By the time the incident became public, researchers estimated that only about 115 million ONE remained under the attacker's on-chain control, with the rest sitting in exchange deposit wallets or already sold.

Harmony suspended its bridge to LayerZero, shipped a patch it told validators to install, and asked exchanges to freeze funds traced to four addresses. It is also evaluating a full chain rollback to cancel the fraudulent supply. That option would undo transactions the network's own consensus had already accepted, including trades made by parties with no connection to the attack.