Weather Witness

L-2: Using ERC721::_mint() It can be dangerous if the receiver is a smart contract that doesn't support ERC721 tokens

Description

The use of ERC721::_mint() in the WeatherNft::fulfillMintRequest function can lead to issues if the recipient address is a smart contract that does not implement the IERC721Receiver interface. Since _mint() does not check whether the recipient can handle ERC721 tokens, it may result in tokens being irreversibly locked in contracts that are not capable of receiving them. This poses a risk of permanently stuck NFTs and loss of functionality for users interacting via contracts.

Risk

Likelihood:

• if only externally owned accounts (EOAs) interact, _mint() will generally work fine.

• when the contract can't control who the recipient is, there's a high chance the recipient could be a contract that doesn’t handle ERC721 tokens properly.

Impact:

• NFTs may be permanently lost or inaccessible if minted to contracts that are not ERC721-compatible.

Recommended Mitigation

Use _safeMint() instead of _mint() to ensure that the receiving address can handle ERC721 tokens. _safeMint() performs a check and reverts the transaction if the recipient is a non-compliant contract.