A hacker has stolen $237,000 from the Polkadot-based cross-chain interoperability protocol Hyperbridge. The attack, which only affected DOT on Ether, resulted in limited liquidity in the bridged DOT pool and a temporary halt to operations. The incident has raised security concerns about the integrity of the Hyperbridge infrastructure. Cybersecurity research company Blocksec Falcon believes the likely root cause of the exploit is a Merkle Mountain Range (MMR) proof replay vulnerability caused by missing proof-to-request binding. This follows a similar incident involving the data indexing protocol SubQuery Network, where hackers exploited an access control data two years ago.