Crypto bridge hacks: risks and secure swap alternatives

DeFi's $2B bridge vulnerability problem

Swap crypto vs bridge crypto

The decentralized finance (DeFi) ecosystem has been significantly impacted by a series of high-profile cross-chain bridge hacks in 2025. These breaches have revealed the vulnerabilities inherent in traditional crypto bridge solutions, resulting in millions of dollars stolen. The need for secure and decentralized crypto swap alternatives like Symbiosis is more apparent than ever.

In this article, we will explore the most significant crypto bridge hacks of 2025, examine their common vulnerabilities, and highlight why swapping crypto securely using solutions like Symbiosis is the safest method for cross-chain transactions.

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Top crypto bridge hacks 2025

Force Bridge exploit – $3.76 million (June 2025)

Details: The Force Bridge, a decentralized crypto bridge connecting the Nervos Network with other blockchains, was exploited in June 2025. Hackers took advantage of access control vulnerabilities within the bridge’s smart contracts, stealing approximately $3.76 million across multiple cryptocurrencies, including USDT, ETH, USDC, DAI, and WBTC.

Method: The attackers gained unauthorized access to critical functions within the Force Bridge's smart contracts, likely due to compromised private keys, which enabled them to initiate unauthorized token swaps and withdraw funds.

Impact: This breach exposed significant vulnerabilities in the access control mechanisms of cross-chain bridges, particularly emphasizing the risks of centralized control and weak smart contract security. It also raised questions about the overall security of blockchain bridge protocols.

Ronin Bridge exploit – $12 million (August 6, 2024)

Details: The Ronin Bridge, a cross-chain bridge that facilitates transfers between Ethereum and the Ronin sidechain, was exploited on August 6, 2024. The exploit occurred due to a faulty upgrade deployment script that failed to call a necessary initialization function, leaving a critical variable uninitialized. This allowed the attackers to withdraw approximately $12 million, including 4,000 ETH and 2 million USDC.

Method: The attackers exploited the uninitialized variable in the bridge's smart contract. This flaw was introduced through the faulty upgrade script, enabling unauthorized withdrawals and bypassing security checks in the bridge protocol.

Impact: This breach highlighted serious vulnerabilities in the upgrade process and smart contract vulnerabilities. It also raised concerns about the security of decentralized finance (DeFi) blockchain interoperability and the infrastructure supporting it.

FEG token bridge exploit – $1.3 million (December 2024)

Details: The FEG Token Bridge, a decentralized cross-chain bridge used for token transfers, was exploited in December 2024. Attackers took advantage of a flaw in the bridge’s relayer contract, allowing them to bypass security measures and withdraw approximately $1.3 million worth of FEG tokens. This attack caused the token’s value to drop by 99%.

Method: The attackers exploited weaknesses in the message verification process of the FEG SmartBridge, which failed to authenticate the sender’s trustworthiness properly. By sending a malicious message that bypassed access control vulnerabilities, they were able to add their contract to the bridge’s whitelist. This enabled them to withdraw tokens across multiple blockchains, including Ethereum, Binance Smart Chain, and Base.

Impact: This breach revealed significant flaws in trust management within cross-chain bridges. The hack led to a massive loss of funds and a dramatic decline in FEG token value. It demonstrates the critical need for enhanced bridge security to prevent unauthorized access and ensure safe cross-chain swaps.