First Flight #2: Puppy Raffle

Summary

Sending an nft to a zero address will revert the selectWinner function.

Vulnerability Details

In the current implementation of the contract, whenever a player is refunded the player address is replaced with a zero addresss. Now as the players array contains this zero address and if the selectWinner function selects this zero address as the winner then _safeMint(winner, tokenId); this line would cause a revert.

Impact

The selectWinner function would revert if the winner is a zero address.

Tools Used

VS code

Recommendations

Move the value of the last index to the refunded address refunded address to the last index and then use the pop method to remove the refunded address instead of setting it to a zero address.