Attacker Exploits Polkadot Token Vulnerability on Ethereum, but Profits are Limited

While cryptocurrency hacks are commonplace, instances where attackers take significant risks only to walk away with relatively small gains are rare. This unusual scenario unfolded on a recent Sunday. An attacker identified a vulnerability in Hyperbridge's cross-chain gateway, which connects various blockchains, and used it to mint 1 billion Polkadot tokens, valued at $1.19 billion, on the Ethereum network.

They then sold these tokens for around $237,000 in ether. This exploit highlights the increasing number of bridge vulnerabilities in 2026, following a $270 million Drift Protocol incident on Solana last month.

The attack targeted Hyperbridge's EthereumHost contract, specifically the validation process for incoming cross-chain messages. Bridges, which facilitate the transfer of coins between blockchains, are often the weakest link in cross-chain architecture due to their admin-level control over token contracts on destination chains. A single validation failure can grant an attacker unlimited supply. The exploit was made possible by a forged message submitted via dispatchIncoming, which was routed to TokenGateway.onAccept.

The request receipts check failed to verify the message against a valid cross-chain state commitment from Polkadot, allowing the gateway to process the message as legitimate. The attacker then executed changeAdmin on the bridged Polkadot token contract, gaining admin rights and minting 1 billion tokens. These tokens were sold through Odos Router V3 into a Uniswap V4 DOT-ETH pool, resulting in approximately 108.2 ETH.

However, the limited liquidity of the bridged DOT pool on Ethereum worked against the attacker, capping their profit. If the same vulnerability were exploited on a deeper pool or a higher-value bridged asset, the losses would have been significantly larger. As of Monday morning, DOT was trading just under $1.20.

The incident was flagged by CertiK, confirming the attack vector and the attacker's profit of approximately $237,000. Hyperbridge has yet to publicly comment on the exploit or disclose whether other bridged token contracts using the same gateway are vulnerable to similar attacks.