Snowman Merkle Airdrop
First Flight #42
Beginner FriendlyFoundrySolidityNFT
100 EXP
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Submission Details
Severity: high
Valid

Lacks access control on `Snowman::mintSnowman` function allows anyone and anytime can mint Nfts freely.

juliancabmar

Description:
The mintSnowman function in the Snowman contract is external and lacks access control, making it vulnerable to infinite free minting for anyone.

@> function mintSnowman(address receiver, uint256 amount) external {
for (uint256 i = 0; i < amount; i++) {
_safeMint(receiver, s_TokenCounter);
​
emit SnowmanMinted(receiver, s_TokenCounter);
​
s_TokenCounter++;
}
}

Impact:
Anyone can mint unlimited Snowman NFTs freely at any time, breaking scarcity and the intended distribution process.

Proof of Concept:
Add the following after the TestSnowmanAirdrop test suite:

function testAnyoneAnytimeCanMintSnowman() public {
vm.prank(bob);
nft.mintSnowman(bob, 10);
​
assertEq(nft.balanceOf(bob), 10);
}

Recommended Mitigation:
Use the onlyOwner modifier on Snowman::mintSnowman declaration.

- function mintSnowman(address receiver, uint256 amount) external {
+ function mintSnowman(address receiver, uint256 amount) external onlyOwner {
for (uint256 i = 0; i < amount; i++) {
// _safeMint(receiver, s_TokenCounter);
​
emit SnowmanMinted(receiver, s_TokenCounter);
​
s_TokenCounter++;
}
}
Updates

Lead Judging Commences

yeahchibyke Lead Judge about 2 months ago
Submission Judgement Published
Validated
Assigned finding tags:

Unrestricted NFT mint function

The mint function of the Snowman contract is unprotected. Hence, anyone can call it and mint NFTs without necessarily partaking in the airdrop.

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