Cryptocurrency hacks have become increasingly common, but instances where attackers take significant risks only to gain minimal rewards are rare. One such incident occurred on Sunday, where an attacker exploited a vulnerability in Hyperbridge's cross-chain gateway, which connects various blockchains, and minted 1 billion Polkadot tokens, valued at $1.19 billion, on the Ethereum network, only to sell them for approximately $237,000 worth of ether.
This exploit highlights the growing list of bridge vulnerabilities in 2026, including a $270 million Drift Protocol exploit on Solana last month. The attack targeted the bridge contract, rather than Polkadot's core network, and the native token DOT remained unaffected. The vulnerability lay in the validation process of incoming cross-chain messages by Hyperbridge's EthereumHost contract before passing them to the TokenGateway. Bridges, which facilitate the transfer of coins between blockchains, are often the weakest link in cross-chain architecture, as they hold administrative control over token contracts on destination chains, making them vulnerable to attacks.
The attacker submitted a forged message via dispatchIncoming, which was routed to TokenGateway.onAccept, and due to a lack of proper validation, the message was processed as legitimate. This allowed the attacker to gain administrative rights over the bridged Polkadot token contract, mint 1 billion tokens, and sell them through Odos Router V3 and Uniswap V4, resulting in a profit of roughly 108.2 ETH.
The limited liquidity in the bridged DOT pool on Ethereum worked against the attacker, capping their potential profit. The incident was flagged by CertiK, which confirmed the attack vector as the Hyperbridge gateway contract, and the attacker's profit was approximately $237,000. Hyperbridge has not publicly commented on the exploit or disclosed whether other bridged token contracts using the same gateway are vulnerable to similar attacks.