Caviar Private Pools - SaeedAlipoor01988's results

Lines of code

https://github.com/code-423n4/2023-04-caviar/blob/cd8a92667bcb6657f70657183769c244d04c015c/src/PrivatePool.sol#L230 https://github.com/code-423n4/2023-04-caviar/blob/cd8a92667bcb6657f70657183769c244d04c015c/src/PrivatePool.sol#L231

Vulnerability details

Impact

Check PoC please.

Proof of Concept

It casts netInputAmount - feeAmount - protocolFeeAmount, which is a uint256, to a uint128. If netInputAmount - feeAmount - protocolFeeAmount is larger than 2 ** 128 - 1, the unsafe cast will only keep its rightmost bits, causing the result to be much smaller.

    // update the virtual reserves
    virtualBaseTokenReserves += uint128(netInputAmount - feeAmount - protocolFeeAmount);
    virtualNftReserves -= uint128(weightSum);

The same is happening for weightSum,

    // calculate the sum of weights of the NFTs to buy
    uint256 weightSum = sumWeightsAndValidateProof(tokenIds, tokenWeights, proof);

If sumWeightsAndValidateProof(tokenIds, tokenWeights, proof) is larger than 2 ** 128 - 1, the unsafe cast will only keep its rightmost bits.

Tools Used

Manually

Recommended Mitigation Steps

use OpenZeppelin’s SafeCast library when casting from uint256 to uint128.