Hyperbridge’s Revised Loss Estimate Reveals $2.5M in Cross-Chain Exploit Damage

The revised loss estimate from Hyperbridge’s cross-chain exploit now stands at $2.5 million, up from an initial figure of $237,000. This increase reflects the full impact of the incident on incentive pools across Ethereum, Base, BNB Chain, and Arbitrum. The exploit, which occurred on April 13, 2026, involved the unauthorized minting of 1 billion bridged DOT tokens and the withdrawal of 245 ETH from the Token Gateway smart contract. The initial estimate underestimated the cascading losses across multi-chain incentive structures. The hackers exploited a flaw in the Merkle Mountain Range proof verification process, where poor input validation and missing boundary checks allowed the manipulation of cryptographic proofs. The vulnerability also enabled an instantaneous transfer of admin control without time locks or protections, facilitating the unauthorized minting. Bridging operations have been suspended while Hyperbridge works with auditors to deploy a patch for the MMR validation flaw. A full forensic investigation is expected to take several weeks or months.