Core Contracts
Regnum Aurum Acquisition Corp
HardhatReal World AssetsNFT
77,280 USDC
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Submission Details
Severity: medium
Valid

Incorrect Tax Handling in Burn Function When feeCollector is Zero address

skidd0016

Link to Affected Code:\

Description:
Here , we can see that its possible to not have a feeCollector.

In the burn function , when the feeCollector is a 0 address , the calculated taxAmount is Neither burned or transfered , it remains in the user's balance.

we can see that regardless of if there is a feeCollector or not, the tax amount is calculated here in the function, so there is an intended taxation:

uint256 taxAmount = amount.percentMul(burnTaxRate);

But if the FeeCollector doesnt exist , the transfer call doesnt happen.

@> _transfer(msg.sender, feeCollector, taxAmount);
​

Impact:

  • Users can bypass the burn tax

  • Incorrect token supply tracking (total supply does not decrease by the full amount).

  • If a user wants to burn a cetain amount they have to increase the amount by the taxAmount in order to achieve that

Proof of Concept:

  1. Set feeCollector = address(0).

  2. User calls burn(1000) with burnTaxRate = 50 (0.5%).

  3. taxAmount = 5 is calculated but not burned or transferred.

  4. User’s balance decreases by 995 instead of 1000.

Recommended Mitigation:

  • If no feeCollector further burn the tax amount

function burn(uint256 amount) external {
uint256 taxAmount = amount.percentMul(burnTaxRate);
_burn(msg.sender, amount - taxAmount);
if (taxAmount > 0) {
if (feeCollector != address(0)) {
super._update(msg.sender, feeCollector, taxAmount);
} else {
_burn(msg.sender, taxAmount); // Burn taxAmount if no feeCollector
}
}
}
Updates

Lead Judging Commences

inallhonesty Lead Judge about 1 month ago
Submission Judgement Published
Validated
Assigned finding tags:

RAACToken::burn incorrectly deducts tax amount but doesn't burn or transfer it when feeCollector is address(0), preventing complete token burns

inallhonesty Lead Judge about 1 month ago
Submission Judgement Published
Validated
Assigned finding tags:

RAACToken::burn incorrectly deducts tax amount but doesn't burn or transfer it when feeCollector is address(0), preventing complete token burns

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