Hacker Creates $1 Billion in Polkadot Tokens, but Only Manages to Steal $250,000

While cryptocurrency hacks are common, it's rare for attackers to take significant risks and end up with relatively small gains. This unusual scenario occurred on Sunday when an attacker exploited a vulnerability in a cross-chain gateway, creating 1 billion Polkadot tokens, valued at $1.19 billion, on the Ethereum network and selling them for approximately $237,000 in ether. The incident highlights the growing issue of bridge vulnerabilities in 2026, following a $270 million exploit on Solana last month. In this case, the attacker targeted the bridge contract, not Polkadot's core network, and the native DOT token remained unaffected.

The vulnerability was found in the way the Hyperbridge EthereumHost contract validated incoming cross-chain messages before passing them to the TokenGateway. Bridges are particularly susceptible to attacks because they hold admin-level control over token contracts on destination chains, making them a weak point in cross-chain architecture. The attack occurred 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 then executed changeAdmin on the bridged Polkadot token contract, transferring admin rights to the attacker's address. With admin control, the attacker created 1 billion tokens and sold them through a Uniswap V4 DOT-ETH pool, extracting roughly 108.2 ETH. However, the limited liquidity in the market worked against the attacker, capping their profits.

The bridged DOT pool on Ethereum had limited depth, and the 1 billion tokens overwhelmed the available liquidity, resulting in the attacker receiving only a fraction of a cent per token. If the vulnerability had been exploited on a deeper pool or a higher-value bridged asset, the losses would have been significantly larger. The incident was flagged by CertiK, which confirmed the attack vector was the Hyperbridge gateway contract and that the attacker profited approximately $237,000 from minting and selling the bridged tokens.