Cross-Chain Bridge Exploits Accounted for 50.1% of All Crypto Stolen in H1 2025, Totaling Over $1.5 Billion

Cross-chain bridges -- protocols that transfer assets between blockchains -- have become the single largest attack surface in crypto, with over $1.5 billion (50.1% of all stolen funds) laundered or stolen through bridge exploits in the first half of 2025 alone. Why it matters: bridges must hold massive reserves of locked assets on both source and destination chains, so they become high-value targets concentrating billions in TVL behind a small set of validator keys or smart contracts; so attackers who compromise even a minority of bridge validators (e.g., Orbit Chain's 7/10 multisig keys in January 2024, losing $81 million) gain full control of all locked funds; so stolen assets are immediately bridged across multiple chains, making recovery and tracing exponentially harder for law enforcement; so legitimate cross-chain users face persistent risk that any bridge they use could be the next $100M+ exploit; so the interoperability layer that is supposed to unify the multi-chain ecosystem instead introduces systemic fragility that undermines confidence in all chains simultaneously. The structural root cause is that bridge security models typically rely on multisig schemes with a small number of validators, lack standardized security auditing requirements, and concentrate enormous asset pools behind infrastructure that is orders of magnitude less battle-tested than the Layer 1 chains they connect.