Possible double spending issue for PirexERC4626 vault

Lines of code Vulnerability details Impact Solmate's ERC20 does not provide option to increase/decrease allowance, and only option to do so is by setting it via approve - which sets this amount directly. This poses a problem of double spending, when a user want to check current allowance, and bad...

Reentrancy can increase allowance can be used to take more funds than expected

Lines of code Vulnerability details Reentrancy can increase allowance can be used to take more funds than expected In the same way as the typical front run of ERC20 approve/transferFrom, you would be able to take money when calling maliciousERC20.beforeApprove hook, this would realize a...

FETH.sol is susceptible to ERC20 approve functionality front-running exploit

Lines of code Vulnerability details Proof of concept The problem is perfectly described here The tldr; is that if you approved a person to spend 100 tokens and then you want to decrease his allowance to 50, if he spends his 100 tokens allowance before you set his allowance to 50 he will be able t...