QuantAMM
QuantAMM
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Submission Details
Severity: low
Invalid

Weight validation missing in QuantAMM pool factory

sabit

Summary

The QuantAMMWeightedPoolFactory contract lacks essential validation for token weights during pool creation, violating a fundamental mathematical requirement of weighted pools. The weights must sum to FixedPoint.ONE (1.0) to ensure correct price calculations and pool operations.

Vulnerability Details

Here's the comment on the contract:

* @param normalizedWeights The pool weights (must add to FixedPoint.ONE)

https://github.com/Cyfrin/2024-12-quantamm/blob/a775db4273eb36e7b4536c5b60207c9f17541b92/pkg/pool-quantamm/contracts/QuantAMMWeightedPoolFactory.sol#L23C1-L23C73

Here are the affected code:

struct NewPoolParams {
string name;
string symbol;
TokenConfig[] tokens;
uint256[] normalizedWeights; // Weights accepted without validation
// ... other fields
}
​
function create(NewPoolParams memory params) external returns (address pool, bytes memory poolArgs) {
// No validation of normalizedWeights
pool = _create(abi.encode(
QuantAMMWeightedPool.NewPoolParams({
// ... parameters
}),
getVault()
), params.salt);
}
​
function createWithoutArgs(NewPoolParams memory params) external returns (address pool) {
// Same issue - no validation of normalizedWeights
pool = _create(abi.encode(
// ... same creation logic
), params.salt);
}
​

https://github.com/Cyfrin/2024-12-quantamm/blob/a775db4273eb36e7b4536c5b60207c9f17541b92/pkg/pool-quantamm/contracts/QuantAMMWeightedPoolFactory.sol#L44

https://github.com/Cyfrin/2024-12-quantamm/blob/a775db4273eb36e7b4536c5b60207c9f17541b92/pkg/pool-quantamm/contracts/QuantAMMWeightedPoolFactory.sol#L131C3-L173C2

https://github.com/Cyfrin/2024-12-quantamm/blob/a775db4273eb36e7b4536c5b60207c9f17541b92/pkg/pool-quantamm/contracts/QuantAMMWeightedPoolFactory.sol#L85C1-L125C6

The weight validation is crucial because:

  1. Price Calculation Formula: P = (Balance_out/Weight_out)/(Balance_in/Weight_in)

    • Incorrect weights directly distort this calculation

    • Example: With weights summing to 1.2 instead of 1.0, prices are off by 20%

  2. Pool Balance Requirements:

    Correct Example (sum = 1.0):
    - Token A: 0.4 (40%)
    - Token B: 0.6 (60%)
    Result: Balanced pricing and swaps
    ​
    Incorrect Example (sum = 1.3):
    - Token A: 0.7 (70%)
    - Token B: 0.6 (60%)
    Result: Overvalued assets, broken swap math
    ​

Impact

  1. Price Distortions:

    • Swaps execute at incorrect prices

    • Arbitrage opportunities emerge

    • Pool value can be extracted

  2. Liquidity Provider Effects:

    • Incorrect share distribution

    • Impermanent loss miscalculations

    • Unintended exposure ratios

  3. Pool Operations:

    • All swap calculations permanently incorrect

    • Join/Exit ratios distorted

    • Fee calculations inaccurate

  4. Connected Systems:

    • Price oracles receive wrong data

    • Connected pools affected

    • Trading strategies compromised

Tools Used

Manual review

Recommendations

function validateWeights(uint256[] memory weights) internal pure {
uint256 sum;
for (uint256 i = 0; i < weights.length; i++) {
sum += weights[i];
}
require(sum == FixedPoint.ONE, "Weights must sum to ONE");
}
​
function create(NewPoolParams memory params) external returns (address pool, bytes memory poolArgs) {
validateWeights(params.normalizedWeights); // Add validation
// Rest of creation logic
}
​
Updates

Lead Judging Commences

n0kto Lead Judge 10 months ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity
Assigned finding tags:

Informational or Gas / Admin is trusted / Pool creation is trusted / User mistake / Suppositions

Please read the CodeHawks documentation to know which submissions are valid. If you disagree, provide a coded PoC and explain the real likelyhood and the detailed impact on the mainnet without any supposition (if, it could, etc) to prove your point.

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