A Cross-Chain Bridge Holds Your Coins While They Travel. Billions Have Been Stolen From Bridges. Here's Why
5 min read
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5 min read
You want to use your ETH on another blockchain. So you use a bridge, and a few minutes later you hold a token that looks like ETH on the new chain. Where did your real ETH go? That question is the whole story of cross-chain bridge hack risk.
Short answer: it is sitting in a vault. And in 2022, Chainalysis counted about $2 billion stolen from bridges in a single year, 69% of everything stolen in crypto that year (Decrypt, reporting Chainalysis, figures seen via search summary). Here is how a bridge works, and why the vault is such a tempting target.
A blockchain is a ledger. Ethereum and Solana are separate ledgers, and neither can see the other. A bridge is the tool that connects them.
Say you want to move 1 ETH to Solana. Most bridges do this in three steps:
Wrapped tokens often have names like wETH. They only keep their value because the vault really holds the original coin. When you want to go back, the bridge destroys your wrapped token and releases the real ETH.
Think of a bridge as a bank vault with a very small door guard.
Every user who bridges ETH adds coins to the same locked pool. Over time that pool can hold hundreds of millions of dollars. A thief does not have to break into thousands of wallets. One successful attack on one bridge can empty everything at once.
Also, a bridge is not one program. It has code on two chains, plus a group of signers or "validators" who confirm deposits. Any weak link can fail. This is why bridges sit between two security models and are only as strong as their weakest part.
These are the three biggest bridge incidents of 2022. Amounts are as reported at the time, in US dollars.
| Date | Bridge | Reported loss | What went wrong |
|---|---|---|---|
| 2 Feb 2022 | Wormhole (Ethereum and Solana) | About $300M to $325M | Attacker faked a deposit proof and minted 120,000 wETH with no real ETH behind it |
| 23 Mar 2022 | Ronin (Axie Infinity) | About $625M | Attacker gained control of 5 of 9 validator keys |
| 2 Aug 2022 | Nomad | About $190M | A flaw let many people copy the exploit and drain funds |
Sources: Wormhole analysis by Merkle Science, Ronin hack summary by Halborn, Nomad report by SecurityWeek. All three were seen only through search summaries, and outlets differ by a few percent on totals.
The attacker abused an old, badly protected check that was meant to verify deposits. They sent fake proof, and the bridge believed a deposit had happened. It then minted 120,000 wETH on Solana that no real ETH backed. Jump Crypto, Wormhole's backer, then put 120,000 real ETH into the bridge to restore the backing (Merkle Science).
Ronin needed 5 of 9 validators to sign off on withdrawals. The attacker got control of five, four belonging to Sky Mavis and one to Axie DAO. They drained 173,600 ETH and 25.5 million USDC. The cause was not a bug in the smart contract. It was access to the keys (Halborn).
Bridge attacks did not stop in 2022. On 18 April 2026, an attacker forged a cross-chain message on the bridge used by Kelp DAO and released 116,500 rsETH, about 18% of that token's supply, worth roughly $292 million (CoinDesk, seen via search summary). The fallout spread to lenders that had accepted the token as collateral. We cover that side in our post on DeFi lending yield and its risks.
Here is a simple way to think about it. Ask four questions before you hold anything that came through a bridge:
A wrapped token carries the risk of the coin plus the risk of the bridge. If the vault is drained, the token can fall far below the price of the real coin, even if the real coin did nothing wrong.
Not all bridges are alike. Some are run by one team, some by many validators, some have insurance, and rules change often. Check the bridge's own security report and recent audits yourself.
When a bridge breaks, the first sign is usually a sharp price move. Watch crypto prices and sentiment on the NetWort Market page, and check how a base coin like Ethereum has behaved through past shocks. It is a quick way to see risk in numbers before it shows up in your portfolio.