Nikolas Sargeant
TL;DR
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Harmony’s ONE token fell approximately 26% after an apparent exploit created around 4 billion new tokens.
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The newly minted tokens equal more than one-quarter of ONE’s previous supply of roughly 15 billion.
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Harmony is working with exchanges to freeze the funds while preparing a patch and considering a blockchain rollback.
Harmony’s ONE token dropped approximately 26% during Asian trading hours on Wednesday after an apparent exploit reportedly created around 4 billion new tokens.
Harmony confirmed the attack in a post on X and said it was coordinating with cryptocurrency exchanges to freeze the affected funds. The Layer 1 blockchain is also preparing a software patch and evaluating whether to roll back the network.
Harmony exploited as on-chain data reveals unauthorized 4B ONE mint (26% of supply) via empty blocks, with 2.8B quickly funneled to exchanges as price crashed while totalSupply endpoint hides the inflation $ONE
— Juiceberg (@the_juice_berg) August 12, 2026
“We are working on a patch and rollback options,” Harmony said, promising another update when additional information becomes available.
Harmony had approximately 15 billion ONE tokens in circulation or in existence before the incident. The creation of another 4 billion represents an increase equivalent to about 26% of that previous supply, raising immediate concerns about dilution and selling pressure.
Why the Exploit Threatens ONE Holders
Harmony is a Layer 1 blockchain designed to support decentralized finance protocols, digital marketplaces, and other decentralized applications.
ONE serves as the network’s native token. Users need it to pay transaction fees, while validators and delegators use it through staking to help secure the blockchain.
An unauthorized increase in supply can undermine the token’s value because every existing ONE represents a smaller share of the total supply. If the attacker successfully moves and sells the newly created tokens, the resulting market supply could place further pressure on the price.
The sharp decline reflects uncertainty over whether Harmony can isolate the fraudulent tokens and prevent them from reaching liquid markets.
One option being evaluated is a blockchain rollback, which would return Harmony to a state before the exploit occurred and continue processing transactions from that earlier point.
Such a move could erase the unauthorized issuance from the network’s accepted history. However, it could also reverse legitimate transfers and transactions completed after the selected rollback point.
Recovering funds becomes particularly difficult when assets have already reached centralized exchanges, bridges or other blockchain networks. Transactions completed outside Harmony’s direct control may not be reversed simply by changing the network’s history.
Rollbacks are also controversial because they conflict with the principle of blockchain immutability—the expectation that confirmed transactions cannot later be altered by developers or validators.
Harmony would therefore need to weigh the benefits of removing the newly minted tokens against potential harm to users who completed legitimate transactions after the exploit.
Ravencoin Incident Highlights Rollback Risks
Harmony’s exploit comes one day after Ravencoin, a separate blockchain based on Bitcoin’s code, considered reversing several days of transactions following a critical block-validation issue.
Some parts of the Ravencoin network accepted invalid blocks, prompting miners to begin rebuilding the blockchain from a point before the flaw occurred.
Although the incidents are unrelated, they demonstrate the difficult trade-offs involved in using rollbacks as a security response. Reversing an attack or software error can restore the intended supply and network state, but it may also erase valid transactions processed after the problem began.
The latest attack is not the first incident involving the unauthorized creation of ONE tokens.
In December 2023, a staking-system bug reportedly generated approximately 146.3 million ONE. Tokens that should have stopped earning staking payouts continued receiving rewards.
Harmony said 74 addresses were involved in that incident. One address received 51.2 million ONE, while approximately 16.4 million of the improperly issued tokens were later transferred to an exchange.
The network responded by releasing an emergency software update and blacklisting addresses holding the unauthorized tokens.
Horizon Bridge Lost $100 Million in 2022
Harmony also suffered one of the cryptocurrency industry’s largest bridge attacks in 2022, when hackers stole approximately $100 million from its Horizon bridge.
The attackers compromised private keys that controlled the bridge, allowing them to withdraw assets. The FBI later attributed the theft to North Korea’s Lazarus Group.
Wednesday’s incident appears structurally different. Rather than stealing assets deposited in a cross-chain bridge, the attacker reportedly exploited Harmony itself to create additional ONE tokens.
Harmony has not yet disclosed the vulnerability behind the exploit, explained how the 4 billion-token estimate was calculated, or identified how far back a potential rollback would extend.
