Core Contracts

Summary

The mintRewards() function in LendingPool.sol is designed to mint RAAC rewards and can only be called by the StabilityPool contract. However, the function is never actually called by StabilityPool.sol, rendering it ineffective. This oversight prevents the intended reward distribution mechanism from functioning correctly.

Vulnerability Details

Affected Function:

mintRewards(address recipient, uint256 amount) in RAACMinter.sol

https://github.com/Cyfrin/2025-02-raac/blob/main/contracts/core/minters/RAACMinter/RAACMinter.sol#L181-L193

The function mintRewards() is intended to reward users by minting RAAC tokens to a specified address. It includes an access control mechanism that restricts calls to the StabilityPool contract. However, upon reviewing the codebase, it was found that StabilityPool.sol does not call this function at any point, leaving it unused.

Root Cause:

• The contract defines a function for minting rewards but never invokes it.

• This results in no RAAC rewards being distributed, leading to a flawed incentive mechanism.

Code Snippet:

Proof of Concept (PoC)

Preconditions:

• The mintRewards() function exists in LendingPool.sol.

• StabilityPool.sol is supposed to call it to distribute RAAC rewards.

Steps to Trigger:

1. Check all instances where mintRewards() is called.

2. Verify that StabilityPool.sol does not invoke it.

3. Confirm that no RAAC rewards are minted.

Impact

The intended reward mechanism for incentivizing users is broken. This could reduce user engagement, affect protocol stability, and lead to dissatisfaction among participants expecting rewards.

Tools Used

Manual

Recommendations

Ensure that StabilityPool.sol properly calls mintRewards() at the appropriate time. A suggested approach is:

1. Identify the Reward Distribution Trigger:

   • Determine the event that should trigger rewards (e.g., liquidations or user participation in the stability pool).

2. Call mintRewards() from StabilityPool.sol:

   lendingPool.mintRewards(user, rewardAmount);

   • Add this call in a relevant function where rewards should be minted.