In a surprising turn of events, a recent crypto hack saw an attacker take a significant risk, but ultimately walk away with relatively little to show for it. On Sunday, an attacker exploited a vulnerability in the Hyperbridge cross-chain gateway, which connects various blockchains, and minted 1 billion Polkadot tokens on the Ethereum network, valued at approximately $1.19 billion. However, the attacker was only able to sell these tokens for around $237,000 worth of ether.
This exploit highlights the ongoing issue of bridge vulnerabilities, with several high-profile incidents occurring in 2026, including a $270 million Drift Protocol drain on Solana. The Sunday attack targeted the bridge contract, rather than Polkadot's core network, and the native DOT token remained unaffected.
The vulnerability lay in the way Hyperbridge's EthereumHost contract validated incoming cross-chain messages before passing them to the TokenGateway. Bridges, which facilitate the transfer of coins between blockchains, remain a weak point in cross-chain architecture due to their admin-level control over token contracts on destination chains. The attack unfolded when the attacker submitted a forged message 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 accepted message executed changeAdmin on the bridged Polkadot token contract, granting the attacker admin rights. With this control, the attacker minted 1 billion tokens in a single transaction and sold them through Odos Router V3 into a Uniswap V4 DOT-ETH pool, extracting roughly 108.2 ETH across multiple swaps. The limited liquidity in the bridged DOT pool on Ethereum worked against the attacker, capping their profit. The pool's limited depth meant that the 1 billion tokens overwhelmed the available liquidity, resulting in the attacker receiving only a fraction of a cent per token.
On a deeper pool or a higher-value bridged asset, the same vulnerability could have produced significantly larger losses. As of Monday morning, DOT was trading just under $1.20. CertiK flagged the exploit, confirming that the attack vector was the Hyperbridge gateway contract and that the attacker profited approximately $237,000 from minting and selling the bridged tokens. Hyperbridge has yet to publicly comment on the exploit or disclose whether other bridged token contracts using the same gateway are vulnerable to the same forged-message attack vector.