How crypto bridges work, and why they keep getting drained

A crypto bridge moves value between blockchains that cannot talk to each other directly. It also concentrates that value in one place. In 2026 that design cost users hundreds of millions of dollars, and one attack alone drained about $292 million.

The $292 million figure comes from Chainalysis, a blockchain analytics firm that studied the April 18 exploit of a bridge route run by the staking protocol KelpDAO. Chainalysis blamed the Lazarus Group, a hacking operation tied to North Korea. LayerZero, the messaging protocol beneath the route, published its own report and reached the same broad conclusion.

What a blockchain bridge actually does

Blockchains do not share a common language. Bitcoin cannot read Ethereum's ledger, and Ethereum cannot see what happens on Solana. A bridge is the workaround. It takes a coin on the first chain, locks it in a contract, then mints a matching token on the second chain to stand in for the original.

Picture a coat check at a venue. Hand over the coat, take a ticket, and that ticket is worth one coat when returned. The locked coins are the coat. The minted token is the ticket. The system works only while the venue honors every ticket with a real coat waiting in the back.

That promise is the soft spot. A bridge holds the real assets. The copies it mints are only as good as the lock behind them.

Why bridges make such rich targets

Two things pull attackers toward bridges. First, the money sits in one place. A busy bridge can hold hundreds of millions of dollars in locked assets, all guarded by the same code and the same operators.

Second is the check. Before a bridge releases funds, something must confirm that the matching tokens were really locked or burned on the other chain. That confirmation is often simpler than the sum it protects. Break the check. The vault opens.

Security firms have watched this for years. Bridges hold only a small slice of the value locked across DeFi, yet they account for a large share of the money stolen from it.

What went wrong at KelpDAO

KelpDAO runs a staking product built around rsETH, a token that stands for staked Ether (ETH). To move rsETH between chains, it used a route built on LayerZero, which passes messages from one blockchain to another. That route leaned on a single verifier.

According to Chainalysis, attackers took over internal data nodes run by LayerZero and knocked out the backups with a flood of traffic. The verifier was left listening only to nodes the attackers controlled. Those nodes reported token burns that never happened. On April 18, 2026, the bridge released about 116,500 rsETH, worth roughly $292 million, against transactions that did not exist.

LayerZero, in its own incident report, said the KelpDAO route used a one-of-one verifier setup, a single check with no second opinion. The company said it had warned against that setup before. After the loss it stopped signing messages for single-verifier routes. KelpDAO shifted rsETH onto a different messaging system.

Here is the uncomfortable part. The code was not broken. The contracts did exactly what they were told, using inputs that were faked upstream. Neither Chainalysis nor LayerZero has said the stolen money was recovered.

A pattern across 2026

KelpDAO was the biggest bridge hit of the year, not the only one. Security firm PeckShield counted eight cross-chain bridge exploits in the first half of 2026, with combined losses near $328.6 million, in figures it reported in May. The protocols differ. The weak spot, that verification layer, keeps turning up.

That share tells the story. A category holding a modest fraction of the value locked in DeFi keeps producing an outsized part of its thefts. The reason is structural, not bad luck.

What to watch

The fix most protocols now point to is redundancy. Instead of one verifier, several independent ones must agree before a bridge releases funds. LayerZero's decision to stop signing for single-verifier routes follows that logic, and so does KelpDAO's switch to another system.

For anyone moving coins across chains, the plain takeaway is that a bridge is a trust decision, not a free teleport. The token on the far side is a claim on assets locked somewhere else. When that lock fails, the claim can fall to nothing. Worth checking before the coins leave the first chain.