If you have spent any time in cryptocurrency, you have probably heard about cross-chain bridges. These tools let you move tokens between different blockchain networks, like sending Ethereum to Solana or moving Bitcoin to a Layer 2 network. They sound convenient, and they are, but they also happen to be the most frequently exploited part of the entire crypto ecosystem. In May 2025 alone, bridge-related exploits contributed to $244 million in total hack losses. Here is everything you need to know about how bridges work, why they get attacked, and how to protect yourself.
The Basics
A cross-chain bridge is a piece of software that connects two or more blockchains and allows them to communicate. Because blockchains like Bitcoin, Ethereum, and Solana operate independently with different rules and programming languages, they cannot natively understand each other. Bridges solve this problem by creating a pathway between networks.
Here is the most common way bridges work. When you want to move, say, 1 ETH from Ethereum to Solana, the bridge locks your 1 ETH in a smart contract on the Ethereum side. Then it mints or releases an equivalent amount of wrapped ETH on Solana. When you want to move back, the wrapped tokens get burned and your original ETH gets unlocked. The locked assets serve as collateral backing the wrapped tokens on the other chain.
With Bitcoin currently trading around $105,652 and Ethereum near $2,536, the total value locked in bridge protocols runs into billions of dollars. That massive pool of locked assets is exactly what makes bridges such attractive targets for hackers.
Why It Matters
Cross-chain bridges matter because the crypto ecosystem is increasingly multi-chain. DeFi protocols exist on Ethereum, Solana, Avalanche, BNB Chain, and dozens of other networks. Users want to move assets freely between these ecosystems without going through centralized exchanges. Bridges provide this functionality, but they introduce significant security risks in the process.
The fundamental problem is that bridges concentrate risk. When billions of dollars of assets are locked in a single bridge contract, that contract becomes one of the highest-value targets in the entire crypto space. The Force Bridge exploit in late May 2025 demonstrated this vividly when $3.9 million was drained through an access control failure. Earlier in May, the Cetus Protocol on Sui lost $220 million through a bridge-related exploit. These are not isolated incidents but a persistent pattern.
Getting Started Guide
If you need to use a bridge, follow these steps to minimize your risk. First, research the bridge thoroughly before using it. Check whether it has undergone professional security audits from reputable firms like Trail of Bits, OpenZeppelin, or ConsenSys Diligence. Look for audit reports published on the project’s website or documentation.
Second, check the bridge’s track record. Has it been operating for a long time without incidents? Projects that have been live for years without exploits generally have more battle-tested code. New bridges may offer better features but carry higher risk due to less testing in production environments.
Third, never bridge more than you can afford to lose. Even well-audited bridges can be compromised. Treat bridge transactions as high-risk operations and limit your exposure accordingly. If you need to move a large amount between chains, consider doing it in smaller transactions over time rather than all at once.
Fourth, prefer bridges that use verified multi-signature security models with transparent validator sets. Bridges that rely on a small number of validators or centralized control present higher counterparty risk. Look for projects that publish their validator lists and governance structures openly.
Common Pitfalls
New users often make several mistakes when using cross-chain bridges. The most dangerous is approving unlimited token spending. When you interact with a bridge, you typically need to grant it permission to spend your tokens. Some bridges request unlimited approval, which means if the bridge is later compromised, the attacker can drain all tokens you have approved, not just the amount you intended to bridge.
Another common mistake is rushing through transactions without verifying the destination address. Bridge interfaces can be spoofed by phishing sites, and sending tokens to the wrong address results in permanent loss. Always double-check the URL and verify the transaction details before confirming.
Users also frequently ignore bridge fees and slippage. Moving assets between chains costs money, and the exchange rate may not be exactly one-to-one. Factor in these costs when deciding whether bridging is worth it, especially for smaller amounts where fees might represent a significant percentage.
Next Steps
Once you understand bridge basics, consider exploring alternatives that may reduce your reliance on them. Some centralized exchanges offer free or low-cost internal transfers between networks, which can be safer for large amounts. Wrapped tokens on major DEXs sometimes offer liquidity paths that avoid bridge interaction entirely. As the ecosystem matures, new interoperability protocols like LayerZero and Chainlink’s CCIP aim to provide more secure cross-chain communication, potentially reducing the risks that current bridges present. Stay informed about these developments as they may offer safer options in the near future.
Disclaimer: This article is for informational purposes only and does not constitute financial or investment advice. Always conduct your own research before making any financial decisions.
Bug bounties are the most cost-effective security investment
244M in bridge hacks just in May 2025 and people still use them without checking the multisig setup. the article nails it though, lock-and-mint is fundamentally broken because the locked side is always a honeypot
bridge_rekt_42 the lock side being a honeypot is the core issue. whoever controls the mint/burn contract basically holds every users funds hostage
locked assets as collateral is the fundamental design flaw. one compromise of the custody contract and everything unravels
the lock and mint model is the whole problem. one custody contract compromise and every wrapped token on the destination chain becomes worthless
lock_mint_flaw_ the lock and mint model is fundamentally broken. one custody contract compromise and every wrapped token on the destination chain becomes worthless instantly
lock and mint is the original sin of bridge design. you are literally creating a centralized custody point on top of decentralized chains. liquidity pools without wrapping are the only model that makes sense
wrap_token_void_ one custody compromise cascading to every wrapped token is exactly what happened with wormhole. 120K eth gone in seconds because one signer key leaked
The industry needs standardized security audit frameworks
Social engineering attacks are becoming more sophisticated
Formal verification should be mandatory for high-value protocols
244M in one month from bridge exploits and teams still launch without formal verification. the cost of an audit is pocket change compared to losing everything
Emil V. 244M in bridge exploits in a single month and teams still skip formal verification. an audit costs 30k. losing 244M is the alternative. the math is obvious
The amount of DeFi exploits is still way too high
eth_staker_ $244M in bridge exploits in May 2025 alone. the numbers are getting worse not better despite more audits
bridge_rekt nailed it. 244M in May 2025 alone and the numbers keep getting worse despite more audits being done than ever. something is structuraly broken
burn_after_read_ the numbers keep getting worse despite more audits because the audit market is a checkbox exercise. firms rubber stamp contracts in 48 hours for a badge. formal verification is the real standard
burn_rate_ audits as a checkbox exercise is exactly right. 30K for an audit vs 244M lost. the math is obvious yet teams still skip formal verification
burn_after_read_ audits being a checkbox is the real problem. firms like CertiK rubber stamp anything in 72 hours. Trail of Bits is better but costs 3x more so teams skip them
Arjun P. CertiK rubber stamping in 72 hours while Trail of Bits costs 3x is the entire audit industry problem in one sentence. you get what you pay for until you lose 200M
244M in bridge exploits in a single month. the lock and mint model is fundamentally broken because one custody compromise cascades to every wrapped token
244M in bridge exploits in May 2025 and teams still launch lock-and-mint designs. one custody compromise and every wrapped token on the destination chain becomes worthless
audits costing 30k vs 244M in losses and teams still skip formal verification. the math is obvious yet the checkbox audit market keeps growing
244M in one month from bridges and teams still ship lock-and-mint. liquidity pool bridges like across and hop exist. the blueprint is public and people still choose the broken model