Harmony's ONE token plunges 40% after exploit mints 4 billion unauthorized tokens

On August 12, 2026, the Layer 1 blockchain platform Harmony suffered an exploit where an attacker minted approximately 4 billion unauthorized ONE tokens, increasing the supply by 26%. The price of ONE plunged up to 40% to around $0.0008, valuing the minted tokens at $3.2 million. Harmony paused its token bridge, asked exchanges to freeze four wallet addresses, and is evaluating a blockchain rollback. This follows Harmony's $100 million Horizon bridge hack in 2022 and a staking bug in 2023.

Unauthorized token minting exploit

• ▪An attacker exploited the Layer 1 blockchain platform Harmony on August 12, 2026, to mint approximately 4 billion unauthorized ONE tokens.
• ▪The unauthorized minting of 4 billion ONE tokens on August 12, 2026, represented an increase of about 26% against the existing supply of roughly 15 billion ONE tokens.
• ▪An X user named Juiceberg reported that the attacker minted the 4 billion ONE tokens on August 12, 2026, by using empty blocks.
• ▪According to X user Juiceberg, the attacker of the August 12, 2026 Harmony exploit had approximately 115 million ONE tokens left to sell on-chain, with about 97% already sent to exchanges.

Emergency response measures

• ▪Harmony stated on August 12, 2026, that it is working on a software patch and evaluating blockchain rollback options to address the unauthorized token minting.
• ▪Following the August 12, 2026 exploit, Harmony instructed its network operators to install an emergency software update to prevent further token minting.
• ▪Following the August 12, 2026 exploit, Harmony paused its token bridge and requested cryptocurrency exchanges to freeze funds traced to four specific wallet addresses linked to the incident.

ONE token price collapse

• ▪The price drop following the August 12, 2026 exploit brought the ONE token to around $0.0008, valuing the 4 billion minted tokens at roughly $3.2 million.
• ▪Following the exploit on August 12, 2026, the price of Harmony's native ONE token plunged by approximately 34% to 40% in Asian morning hours.

Blockchain rollback considerations

• ▪A potential blockchain rollback would return the Harmony network to its state before the August 12, 2026 exploit, effectively removing subsequent transactions from the blockchain's history.
• ▪The August 12, 2026 Harmony exploit occurred one day after the Ravencoin blockchain faced its own potential rollback due to a critical block flaw.
• ▪Industry participants view blockchain rollbacks as antithetical to the core principle of immutability, and rollbacks become harder once funds reach exchanges.

Prior Harmony security breaches

• ▪In December 2023, a bug in Harmony's staking system caused the unauthorized creation of approximately 146.3 million ONE tokens across 74 addresses.
• ▪In June 2022, Harmony's Horizon cross-chain bridge was exploited for nearly $100 million, an attack the FBI later attributed to North Korea's Lazarus Group.

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