# The check rewardSelector != ZERO BYTES4 && rewardDestination.isContract() could be improved Low/Info · 0xSimao · CDP stablecoin · 14th March 2025 Finding I-5 of the Felix Price Feeds security review. - Protocol: https://www.usefelix.xyz/ - Report: /reports/felix - Source: https://github.com/0xSimao/audits/blob/main/0xSimao/2025-03-14-felix.pdf --- **Description:** When the destination reward is a contract and the selector is not 0, the function is called on the contract. However, there seems to be no logical scenario to have a reward selector different than 0 and the reward destinaton not being a contract. In case this happens by mistake, rewards could be sent to the destination contract without calling the function, which could be problematic. **Recommended Mitigation:** It would be better to either revert in this case or perform the contract check when setting the reward selector. **0xSimao:** Fixed in [#0d6233e](https://github.com/felixprotocol/felix-contracts/commit/0d6233ec9ad2a6c98e6b88f36537344c2699ff14). --- Related findings: - [BaseRouter, _bundleInternal(...) Action.Flashloan does not check if the selector matches xBundle(...)](https://0xsimao.com/findings/fuji-finance-bundle-internal-flashloan-matches): Fuji Finance - [Missing key zero value check](https://0xsimao.com/findings/codeup-missing-key-zero-value): CODEUP - [Unnecessary currentEpoch zero check in StandardGovernor and ThresholdGovernor](https://0xsimao.com/findings/m-0-current-epoch-zero-threshold): M^0 Minter Gateway - [MapleLoan, skim() has no zero address transfer check.](https://0xsimao.com/findings/maple-finance-iii-skim-zero-address-transfer): Maple Finance