Harmony says attacker minted ~4 billion ONE; token drops 26% as team weighs a rollback

An apparent exploit on the Harmony blockchain created roughly 4 billion ONE tokens early Wednesday, and the network's native token fell about 26% during Asian morning hours, CoinDesk reported. Harmony confirmed the incident in a post on X, saying it was working with exchanges to freeze funds and preparing a software fix.

"We are working on a patch and rollback options," the team said in that post, quoted by CoinDesk, adding it would update when it had more information.

The scale is the story. Roughly 15 billion ONE existed before the incident, so 4 billion newly minted tokens amount to an increase of about 26% — more than a quarter of the supply — arriving in a single event. ONE is the asset used to pay transaction fees and secure the chain, so the mint is a solvency problem for the token itself, not a theft of assets sitting on top of it.

A rollback would return the network to a state before the exploit and continue from there, discarding transactions accepted after that point. That can strip an attacker of tokens still on-chain, but the tactic degrades fast once funds reach exchanges or bridge out — which is why the freeze requests and the rollback talk are happening simultaneously. It also means legitimate transactions made after the cutoff get erased alongside the attacker's.

Harmony has not explained the vulnerability, has not shown how the 4 billion figure was derived, and has not said how far back a rollback would reach. No exchange has publicly confirmed a freeze.

The timing is awkward: Ravencoin, a separate and unrelated chain built from Bitcoin's code, faced its own possible rollback a day earlier after parts of its network accepted invalid blocks, with miners rebuilding from before the flaw and several days of transactions at risk, per CoinDesk.

Key facts

• ONE fell ~26% in Asian morning hours Wednesday, Aug. 12 (CoinDesk).
• ~4 billion ONE apparently minted, against a pre-incident supply of ~15 billion — roughly a 26% increase (CoinDesk).
• Harmony confirmed the attack on X and said it is coordinating exchange freezes and preparing a patch, with rollback under consideration (Harmony's X post, via CoinDesk).
• December 2023: a staking bug improperly minted ~146.3 million ONE across 74 addresses; one received 51.2 million, and ~16.4 million moved to an exchange. Harmony shipped an emergency update and blacklisted the addresses (CoinDesk).
• June 2022: ~$100 million drained from Harmony's Horizon bridge via compromised private keys; the FBI attributed it to North Korea's Lazarus Group (CoinDesk).

The real-world read

This is Harmony's third unauthorized-minting or key-compromise event in four years, and the second involving ONE created out of nothing. The 2023 playbook — emergency patch plus blacklisting — is being reached for again, at roughly 27 times the scale.

Two things are conspicuously absent. First, the 4 billion figure is the team's own, published without the on-chain accounting to support it; that number belongs to an interested party until someone independent reproduces it. Second, "rollback options" is doing quiet work: Harmony spent 2023 insisting blacklisting was sufficient, and a rollback is a materially larger admission — that the chain's accepted history is negotiable when the loss is big enough. Users whose legitimate transactions land inside the reverted window would pay for the fix.

Also unsaid: how the mint was possible at all. Absent a root cause, there is no basis to assume the hole is closed.

Opinion, and whose

No named analyst forecast appears in the reporting. CoinDesk's framing — that Harmony and Ravencoin together illustrate the trade-off in rollbacks, where undoing an attack also undoes legitimate activity — is CoinDesk's editorial read, not a claim by either project. Harmony's assertion that a patch and freezes will contain the damage is the team's own position and is unverified.

Sources

• CoinDesk (Aug. 12, 2026), "Harmony's ONE dives 26% after attack appears to create tokens equal to quarter of supply" — the price move, the ~4 billion and ~15 billion supply figures, Harmony's X statement, the 2022 Horizon and December 2023 minting history, and the Ravencoin comparison. Marked by CoinDesk as a developing story. Secondary reporting; its primary source for the incident is Harmony's own X post.
• Harmony (via CoinDesk) — the confirmation and the "patch and rollback options" quote. Statements from the affected party, uncorroborated as of publication.
• The CoinDesk page also carried an unrelated promotional item on Zcash's Tachyon upgrade. It is project-side messaging, not reporting, and none of it is used here.

Not financial advice. Nothing here is a recommendation to buy or sell anything.