Harmony Protocol’s native ONE token fell 40% on Wednesday after the Layer-1 blockchain confirmed an exploit that allowed an attacker to mint 4 billion ONE tokens without authorization.
The attacker moved about 2.8 billion of the newly created tokens to crypto exchanges, according to on-chain analyst Juiceberg. Around 97% of the minted supply was either sold or placed in deposit wallets linked to potential sales.
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
How the Harmony exploit unfolded
The unauthorized minting was first detected through empty blocks on the Harmony network. The large increase in ONE’s supply quickly put pressure on the token as traders reacted to the possibility of heavy selling.
Harmony later confirmed the exploit and said it was working with exchanges to freeze the affected funds. The protocol identified four wallet addresses connected to the incident and urged exchanges to block transactions involving them.
Harmony also paused its bridge to stop the attacker from moving funds across networks. Validators have since been instructed to install a patch designed to prevent further unauthorized minting. The team said it will provide another update on dealing with the tokens that have already been created.
ONE dropped from $0.00124 to $0.000535 before recovering slightly to around $0.000759. Trading volume surged more than 4,000% as holders rushed to sell.
Related: Altura to Shut Down Stablecoin Yield Vault After Surge in Withdrawals
What Happens Next for Harmony
The exploit has also drawn attention from Coin Bureau, which highlighted the scale of the unauthorized mint and its potential impact on ONE holders.
The next few days could be important for Harmony as the network works to contain the damage and restore confidence. Exchanges are expected to continue working with the protocol to identify and freeze funds linked to the attacker.
A possible rollback could also become part of the discussion, although reversing transactions would raise questions around transaction finality and whether the Harmony community supports such a move.
The protocol will also need to provide clearer information about the total number of ONE tokens created, where the unauthorized tokens were sent and how many remain available for sale.
For the market, ONE’s price performance will remain a key indicator of whether investors regain confidence once Harmony provides more details about the exploit and its response.
Harmony faces additional major security problems
In June 2022, its Horizon bridge was exploited for nearly $100 million in crypto assets, including Ethereum and stablecoins. Lazarus Group also moved large amounts of Ethereum obtained through the Harmony Bridge hack.
The FBI later linked that attack to North Korean hacking groups Lazarus Group and APT38. Harmony launched its mainnet in 2019 and uses ONE for transaction fees, staking and governance.
The latest exploit now raises new concerns about the network’s token supply and security as validators work to contain the damage.
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