FutureSwap protocol on Arbitrum is attacked again: hacker exploits reentrancy vulnerability, loses $74,000

【ChainNews】FutureSwap has recently encountered trouble on Arbitrum. According to analysis by the security team BlockSec, this DeFi protocol was targeted by hackers in two consecutive attacks within just a few days, making it a rollercoaster.

After the first attack, the hackers did not stop. Instead, three days ago, they used a carefully crafted reentrancy function (0x5308fcb1), exploiting a logical vulnerability in the protocol to wildly over-mint LP tokens. This is not a clever trick; it’s the common reentrancy attack—calling the contract function again before the transaction completes to bypass balance checks.

What’s more cunning is that the hackers were very patient. After minting the LP tokens, they waited for the cooling-off period to end. Once the time was right, they immediately redeemed these over-collateralized assets, successfully cashing out about $74,000. In just a few days, a single vulnerability was drained dry.

What does this tell us? Every protocol in the DeFi ecosystem must be extremely cautious. Although reentrancy vulnerabilities are an old problem, hackers can still find opportunities if defenses are insufficient.