$1 Billion in Polkadot Tokens Minted on Ethereum, but Attacker Only Nets $250,000

Cryptocurrency hacks have become all too common, but cases where attackers take significant risks only to gain minimal profits are rare. One such instance occurred 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 $1.19 billion. However, they were only able to sell them for around $237,000 worth of ether.

This exploit highlights the growing concern of bridge vulnerabilities in 2026, following a $270 million Drift Protocol exploit on Solana last month. The attack targeted the bridge contract, not Polkadot's core network, and the native DOT token remained unaffected. The vulnerability was found 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, 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 attack involved submitting 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, transferring admin rights to the attacker's address. With admin control, the attacker minted 1 billion tokens and sold them through Odos Router V3 into a Uniswap V4 DOT-ETH pool, extracting approximately 108.2 ETH. 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. CertiK identified the exploit, confirming that the attack vector was the Hyperbridge gateway contract and the attacker profited around $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 attack vector.