A hacker exploited the Polkadot-based cross-chain interoperability protocol Hyperbridge, netting about $237,000 and raising renewed security concerns about blockchain bridge infrastructure.
An attacker minted 1 billion bridged Polkadot (DOT) tokens in a single transaction on Hyperbridge, according to blockchain data shared by cybersecurity platform CertiK.
CertiK said the hacker managed to mint the tokens after he “slipped through a forged message to change the admin of Polkadot token contract on Ethereum.” However, the thin liquidity on Ethereum’s bridged DOT pool was overwhelmed by the 1 billion bridged DOT tokens, shrinking the attacker’s profits to just 108.2 Ether (ETH), worth around $237,000, after the swap.
Cybersecurity research company Blocksec Falcon said the likely root cause of the exploit was a Merkle Mountain Range (MMR) proof replay vulnerability caused by missing proof-to-request binding, though the final root cause has not yet been confirmed by the protocol.
Hyperbridge paused operations after the attack while the team worked on an upgrade, with contributor Web3 Philosopher saying the initial diagnosis pointed to a malicious proof that fooled the protocol’s Merkle tree verifier. Blockchain bridges let users move tokens and data between different networks.
The exploit is notable because Hyperbridge has marketed itself as a proof-based interoperability layer built to deliver “full node security” for crosschain bridges. The incident also follows Aethir’s disclosure last week that it had contained a separate bridge exploit and kept user losses below $90,000.
Cointelegraph has contacted Hyperbridge for comment on the root cause of the exploit.
The exploit only affected DOT on Ethereum that was bridged through Hyperbridge, while native DOT tokens and the wider Polkadot ecosystem remain unaffected, Polkadot noted in a Monday X post.
The native DOT token briefly dipped to a daily low of $1.16 on Monday, before recovering to trade above $1.19 at the time of writing, according to CoinGecko.
DOT/USD, 24-hour chart. Source: CoinGecko
Hackers exploit SubQuery network for $130,000
Security incidents continue to hit crypto protocols despite a sharp year-over-year drop in DeFi exploit losses.
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On Sunday, the data indexing protocol SubQuery Network was also exploited for around $130,000 due to missing access control data that exposed the code written over two years ago.
The vulnerability enabled the attacker to set his own contract as the withdrawal target for staking rewards, blockchain security auditor Pashov said in a Sunday X post.
Hackers stole over $168 million from 34 decentralized finance (DeFi) protocols in the first quarter of 2026, marking a significant decline from the $1.58 billion stolen in the first quarter of 2025, when the record $1.4 billion Bybit hack occurred.
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