Fjord Token Staking

Summary

To receive ERC721 tokens which is called upon a safe transfer, the contract must implement the onERC721Received function.
The onERC721Received function is called when the contract receives an ERC721 token by invoking safeTransferFrom function.
However, the FjordStaking contract doesn't have the onERC721Received function.
The FjordStaking contract receives ERC721 tokens from the Sablier contract, so it must implement the onERC721Received function.

Vulnerability Details

https://github.com/Cyfrin/2024-08-fjord/blob/main/src/FjordStaking.sol#L435

Impact

The unimplemented onERC721Received function can cause the contract to not receive ERC721 tokens from the Sablier contract.

Tools Used

Manual review

Recommendations

It's recommended to implement the onERC721Received function in the FjordStaking contract.