Submitted by cccz, also found by 0x52, 0xYamiDancho, csanuragjain, GimelSec, gzeon, hickuphh3, horsefacts, hyh, IllIllI, kenzo, leastwood, PPrieditis, reassor, unforgiven, WatchPug, and danb
The passThruGate function of the SpeedBumpPriceGate contract is used to charge NFT purchase fees.
Since the price of NFT will change due to the previous purchase, users are likely to send more ether than the actual purchase price in order to ensure that they can purchase NFT. However, the passThruGate function did not return the excess ether, which would cause asset loss to the user.
Consider the following scenario:
https://github.com/code-423n4/2022-05-factorydao/blob/e22a562c01c533b8765229387894cc0cb9bed116/contracts/SpeedBumpPriceGate.sol#L65-L82
illuzen (FactoryDAO) confirmed, but disagreed with severity
illuzen (FactoryDAO) resolved:
Justin Goro (judge) commented:
