[Solidity] Reentrancy vulnerability

Reentrancy vulnerability is a type of vulnerability that occurs when a contract calls an external contract in a way that allows the external contract to call back into the original contract before the original contract has finished executing. This can lead to unexpected and potentially malicious behavior.

The problem is the withdraw function updates balance after transfered successfully to sender. Thefore, if an attacker were to create a malicious version of the IERC20 contract that calls the withdraw function …

solidity vulnerability