Harmony's ONE exploit — what happens when a blockchain mints billions out of thin air

Harmony, a layer-1 blockchain, confirmed on August 12 that an attacker minted roughly 4 billion of its ONE tokens without permission — about 26 percent of the supply — by exploiting a flaw in the network's code. On-chain researchers estimated that around 2.8 billion of those tokens were quickly moved to exchanges and sold, and ONE fell by more than a third to a record low near $0.00077. Harmony has shipped an emergency patch to stop further minting and is now weighing whether to roll the chain back.

"Minting" means creating new tokens. Normally a blockchain only issues new coins under strict rules that every computer on the network agrees to. Here, an analyst who goes by Juiceberg said the attacker found a way to produce ONE through empty blocks, sidestepping those rules. Harmony has not independently confirmed the exact numbers, and even its own supply tracker did not immediately reflect the new tokens — a sign of how confusing these events can be while they unfold.

The fix targets two weaknesses in how Harmony passes transaction results between parts of its network. In simple terms, one flaw let a receipt be accepted without the required approvals, and another let an already-used receipt be replayed so that funds were credited twice. Harmony's signed update, v2026.1.1, closes both paths, and the team told validators to install it. It also paused its bridge and published four wallet addresses tied to the attacker, asking exchanges to freeze anything traced to them.

The harder question is what to do about the tokens that already exist. Harmony said it is considering a rollback — returning the network to a point before the attack and continuing from there. A rollback can erase the theft, but it also erases every ordinary transaction made after that moment, so it is a heavy decision that undoes real users' activity alongside the attacker's. The team has not committed to one.

This is not Harmony's first crisis. In June 2022, hackers drained about $100 million from its Horizon bridge, an attack the FBI later tied to North Korea's Lazarus Group. ONE now carries a market value around $11.5 million and sits outside the top 1,000 tokens, more than 99 percent below its 2021 peak.

For newcomers, the lesson is less about ONE specifically and more about how to act when a project is under attack. Prices swing violently and rumors outrun facts, so this is the worst time to make rushed trades. Rely on the project's official channels for confirmed information, be wary of anyone offering to "help recover" your funds, and remember that in moments like this, doing nothing is often the safest move.