Harmony Plans Rollback After Exploit Forged 3.01 Trillion ONE

Network would erase post-attack transactions and restart both shards from clean checkpoints

TL;DR

• Harmony plans to roll back both shards to a pre-exploit state after determining that an attacker forged 3.01 trillion ONE.
• The recovery would erase legitimate transactions alongside malicious activity because forged tokens had already spread through wallets and services.
• Harmony traced the exploit to reusable cross-shard receipts and chose a fixed rollback over burns, blacklisting, selective replay or token migration.

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Harmony plans to roll back its blockchain to its last clean state before an unauthorized ONE mint, erasing all subsequent blocks and transactions after determining that an attacker forged 3.01 trillion ONE. The Layer 1 network said the exploit stemmed from a cross-shard receipt-verification flaw that allowed valid receipts to be reused, creating new ONE without a corresponding debit elsewhere.

The network disclosed the detailed recovery plan on Aug. 17, 2026. Harmony intends to restore both chains in its sharded network to their state at Aug. 11, 2026, 23:25:37 UTC, before the first confirmed forged mint. Legitimate user transfers, purchases, sales and other transactions confirmed after the cutoff would be removed together with the malicious activity.

Harmony selected that recovery point because the first forged tokens appeared in the next relevant Shard 0 block, numbered 92,730,036. The recovery would use replacement databases rather than simply moving the existing chain head backward. Harmony's upgraded client, v2026.1.2, is designed to reject block hashes associated with the exploit, while the team warned that a simpler built-in revert could leave unwanted state behind and contribute to another failure.

Harmony said an independent security firm reviewed the exploit and agreed with the rollback approach. The network considered a targeted burn first, but the forged ONE had already moved into exchanges, trading pools and smart contracts. Harmony determined that destroying those tokens where they currently sat could remove assets belonging to innocent users who had subsequently received or interacted with them.

A wallet blacklist was rejected because it would leave the illegitimate supply in the network. Selectively replaying legitimate transactions was deemed “unworkable” because blockchain state had already changed, while a full token migration was rejected because Harmony concluded it would cause excessive disruption across the user base.

“Of the options we studied, one fixed rollback window is the fairest and most secure,” Harmony said. “It applies one rule to everyone, removes the forged state, and carries the lowest risk of another attack or consensus failure.”