Description

MorphoVaultStrategy performs token swaps on Uniswap for backgroundSwap and _autoCompoundRewards. Prior to a swap, the validateFeeTier function in the UniswapV3HelperV1 library checks the pool fee:

function validateFeeTier(uint24 fee) public pure {
    if (fee != 500 && fee != 3000 && fee != 10000) {
        revert InvalidFeeTier();
    }
}

The validateFeeTier function accepts only a 0.05%, 0.3%, or 1% pool fee for Uniswap swaps. However, Uniswap V3 includes a 0.01% fee tier↗ (100 basis points), particularly beneficial for stablecoin trading.

Consequently, swaps that use the 0.01% fee tier are incompatible with MorphoVaultStrategy.

Impact

MorphoVaultStrategy cannot execute swaps on Uniswap pools with the 0.01% fee tier, potentially missing optimal trading routes for stablecoin pairs.

Recommendations

We recommend updating the validateFeeTier function to support the 0.01% (100) fee tier:

function validateFeeTier(uint24 fee) public pure {
-    if (fee != 500 && fee != 3000 && fee != 10000) {
+    if (fee != 100 && fee != 500 && fee != 3000 && fee != 10000) {
        revert InvalidFeeTier();
    }
}

Remediation

This issue has been acknowledged by Blueprint Finance, and fixes were implemented in the following commits:

• 29666589↗
• b23b1095↗