Attacker Generates $1 Billion in Polkadot Tokens on Ethereum but Only Manages to Steal $250,000

While cryptocurrency hacks are common, instances where attackers take significant risks and end up with relatively little are rare. This unusual scenario unfolded on Sunday when an attacker exploited a vulnerability in Hyperbridge's cross-chain gateway, which connects different blockchains.

The attacker generated 1 billion Polkadot tokens, valued at $1.19 billion, on Ethereum and then sold them for approximately $237,000 in ether. This exploit is the latest in a growing list of bridge vulnerabilities in 2026, including a $270 million drain on Solana's Drift Protocol last month.

The attack targeted the bridge contract and not Polkadot's core network, with the native DOT token remaining unaffected. The vulnerability was found in how Hyperbridge's EthereumHost contract validates incoming cross-chain messages before passing them to the TokenGateway. Bridges are often the weakest link in cross-chain architecture as they hold admin-level control over token contracts on destination chains, making them vulnerable to attacks.

The attack began when the attacker submitted a forged message via dispatchIncoming, which was then routed to TokenGateway.onAccept. However, 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 then executed changeAdmin on the bridged Polkadot token contract, giving the attacker admin rights. With these rights, the attacker generated 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.

The limited liquidity in the market worked against the attacker, capping their profit. The bridged DOT pool on Ethereum had limited depth, meaning the 1 billion tokens overwhelmed the available liquidity, resulting in the attacker receiving only a fraction of a cent per token.

If the attack had occurred 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. CertiK confirmed the attack vector was the Hyperbridge gateway contract and that the attacker made approximately $237,000 from the exploit. Hyperbridge has yet to comment on the exploit or disclose whether other bridged token contracts using the same gateway are vulnerable to the same attack.