Harmony ONE Plunges 40% After Reported 4B Token Mint Exploit

Harmony’s ONE token plunged nearly 40% on Wednesday after an attacker reportedly created roughly 4 billion tokens without authorization and moved billions of ONE toward centralized exchanges.

Harmony is working with exchanges to stop and freeze the affected funds while developers prepare a patch and evaluate possible rollback options. The project has not yet published a final loss estimate or technical post-mortem.

ONE traded near $0.000746 at the latest check, down about 39.8% over 24 hours after falling as low as $0.0005735. Trading volume surged above $40 million, more than 3,600% higher than the previous day.

Attacker Reportedly Creates 4 Billion ONE

Onchain researcher Juiceberg traced roughly 4 billion newly created ONE, equivalent to about 27% of the roughly 14.9 billion tokens circulating before the incident. Around 2.8 billion ONE were subsequently routed toward exchanges.

Roughly 115 million ONE remained available onchain in the wallets being tracked after the larger transfers. The exchange movements do not establish that every token was sold, but they substantially increased the amount positioned where liquidation could occur.

The mint also exposed an unusual supply-accounting problem. Standard totalSupply queries initially failed to reflect the additional tokens, allowing the newly created supply to remain hidden from conventional checks while the transactions were already occurring. Harmony has not yet confirmed the exact mechanism behind that behavior.

The approximately 4 billion ONE figure remains an onchain estimate pending Harmony’s full technical review.

Harmony Considers Patch And Rollback

Developers are now working on a network patch while evaluating whether a rollback could form part of the recovery process. Exchange cooperation is also central because such a large portion of the suspected unauthorized supply moved toward centralized trading venues shortly after creation.

Harmony previously faced another inflation vulnerability in 2023 when flawed staking logic generated 146.28 million ONE across 74 delegator addresses. Matured undelegations were repeatedly included in payouts because they were not correctly cleared from network state, forcing an emergency hard fork at block 51,118,080.

The latest event is considerably larger, with the reported 4 billion ONE mint representing more than 27 times the amount created during the 2023 staking failure.

Harmony Faces Another Major Security Crisis

Harmony also suffered the $100 million Horizon Bridge theft in June 2022. The FBI later attributed that attack to North Korea’s Lazarus Group, which compromised the bridge before moving stolen assets through laundering infrastructure.

The new mint lands after crypto hacks generated $210.3 million in losses across 30 major incidents in July, led by the expanding Coldcard wallet drains and a series of bridge, oracle and governance failures.