Harmony's ONE token fell nearly 40% on Wednesday after an attacker reportedly minted approximately 4 billion tokens without authorization and transferred billions of ONE toward centralized exchanges.

Harmony is coordinating with exchanges to halt and freeze the affected funds while developers prepare a network patch and assess potential rollback options. The project has not yet released a final loss estimate or a full technical post-mortem. Unauthorized minting attacks are particularly damaging for Layer-1 blockchains because they directly dilute existing token holders and compromise the supply integrity that underpins the network's value proposition — a more fundamental failure than a bridge or wallet exploit, which typically targets existing assets rather than creating new supply.

At the latest check, ONE traded near $0.000746, down approximately 39.8% over 24 hours after dropping to a low of $0.0005735 — a new all-time low reached on August 12. Trading volume surged above $40 million, representing an increase of more than 3,600% compared to the previous day.

Attacker Reportedly Mints 4 Billion ONE

Onchain researcher Juiceberg traced roughly 4 billion newly created ONE, equivalent to approximately 27% of the roughly 14.9 billion tokens in circulation before the incident. Around 2.8 billion ONE were subsequently routed toward exchanges. After the larger transfers, approximately 115 million ONE remained available onchain in the wallets under surveillance.

The movement of tokens toward exchanges does not confirm that all were sold, but it significantly increased the volume of tokens positioned where liquidation could take place.

The mint also revealed an unusual supply-accounting anomaly. Standard totalSupply queries initially failed to reflect the additional tokens, allowing the newly created supply to remain concealed from conventional monitoring even as transactions were already underway. This type of concealment is uncommon, as most minting exploits are immediately visible through standard supply queries, and it raises questions about whether the vulnerability involved deeper consensus-layer or state-management behavior rather than a simple smart contract flaw. Harmony has not yet confirmed the precise mechanism responsible for this behavior, and the approximately 4 billion ONE figure remains an onchain estimate pending the project's complete technical review.

Harmony Considers Patch and Rollback

Developers are now working on a network patch while evaluating whether a rollback could play a role in the recovery effort. Rollbacks — retroactively reversing transactions by reverting the chain to an earlier state — are among the most contentious decisions in blockchain governance, as they tension the principle of transaction immutability against the need for damage control. Ethereum's hard fork following the 2016 DAO hack, which created Ethereum Classic as the unforked chain, remains the most prominent precedent for how rollback decisions can permanently split a community.

Cooperation from exchanges is a critical component, given that a substantial portion of the suspected unauthorized supply was moved to centralized trading platforms shortly after creation. The reliance on exchange coordination underscores how even decentralized protocols depend on centralized infrastructure as a line of defense when attacks involve off-chain liquidity venues.

Harmony previously encountered a separate 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 properly cleared from the network state, necessitating an emergency hard fork at block 51,118,080.

The current event is significantly larger, with the reported 4 billion ONE mint amounting to more than 27 times the volume produced during the 2023 staking failure.

Harmony Faces Another Major Security Crisis

Harmony was also the victim of the $100 million Horizon Bridge theft in June 2022. The FBI subsequently attributed that attack to North Korea's Lazarus Group, which compromised the bridge before moving stolen assets through laundering infrastructure. The combination of the Horizon Bridge attack, the 2023 staking inflation bug, and now the 4 billion token mint places Harmony among the most repeatedly exploited Layer-1 networks, a track record that complicates trust recovery with both users and exchange partners.

The new incident follows a broader wave of crypto exploits. In July, crypto hacks generated $210.3 million in losses across 30 major incidents, driven by the expanding Coldcard wallet drains alongside a series of bridge, oracle, and governance failures.

Harmony has not yet confirmed how the 4 billion ONE were created, how much successfully reached exchanges, how much has been frozen, or whether a rollback will be carried out. Key open questions include whether the supply-accounting anomaly can be fully explained, whether exchange freezes will cover a meaningful portion of the routed tokens, and how the community will respond to any rollback proposal. ONE remains near $0.000746 after touching its new all-time low of $0.0005735 on August 12.