Attacker Exploits Polkadot Token Vulnerability on Ethereum, Nets Only $250,000

Cryptocurrency hacks are a common occurrence, but instances where attackers take significant risks only to reap modest rewards are rare. One such incident occurred on Sunday, when an attacker exploited a vulnerability in a cross-chain gateway, minting 1 billion Polkadot tokens on Ethereum and selling them for approximately $237,000 in ether.

This exploit highlights the growing list of bridge vulnerabilities in 2026, following a $270 million Drift Protocol incident on Solana last month. The attack targeted the bridge contract, not Polkadot's core network, and the native DOT token remained unaffected. The vulnerability lay in the validation process of incoming cross-chain messages by Hyperbridge's EthereumHost contract. 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 minting capabilities. The attack began with the submission of 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 a changeAdmin function 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 around 108.2 ETH. However, the limited liquidity in the bridged DOT pool on Ethereum worked against the attacker, capping their profit. The same vulnerability could have resulted in significantly larger losses if it had occurred on a deeper pool or a higher-value bridged asset.

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 profited around $237,000 from minting and selling the bridged tokens. Hyperbridge has not publicly commented on the incident or disclosed whether other bridged token contracts using the same gateway are vulnerable to the same attack vector.