DatingDapp
AI First Flight #6
Beginner FriendlyFoundrySolidityNFT
EXP
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Submission Details
Severity: high
Valid

H-1: likeUser() never credits userBalances — every like payment is permanently locked

hatchworker

H-1: likeUser() never credits userBalances — every like payment is permanently locked

Summary

likeUser is payable and collects msg.value, but never executes userBalances[msg.sender] += msg.value (verified by grep: userBalances appears only as reads/zeroing in matchRewards). The README promises mutual matches receive pooled like payments minus a 10% fee; in reality the match MultiSig is always funded with 0 ETH, totalFees stays 0 forever, and withdrawFees() always reverts. Every ETH ever sent to likeUser is bricked with zero recovery path.

Root cause

function likeUser(address liked) external payable {
require(msg.value >= 1 ether, "Must send at least 1 ETH");
...
likes[msg.sender][liked] = true;
emit Liked(msg.sender, liked);
if (likes[liked][msg.sender]) { ... matchRewards(liked, msg.sender); }
}
and inside matchRewards, matchUserOne/matchUserTwo read userBalances (always 0), so totalRewards = 0, matchingFees = 0, and the deployed MultiSigWallet is funded with .call{value: 0}.

PoC (Foundry, PASS)

test_H1_likePaymentsPermanentlyLocked: Alice and Bob mint profiles, Alice likes Bob (1 ETH), Bob likes Alice (1 ETH, triggering the match). Asserts: registry balance == 2 ETH, both userBalances == 0, the deployed MultiSig holds 0 ETH, withdrawFees() reverts. PASS.

Recommended mitigation

Credit the payment: userBalances[msg.sender] += msg.value; in likeUser (and refund msg.value - 1 ether excess or revert on overpayment). Add a rescue path for stuck funds.

Updates

Lead Judging Commences

ai-first-flight-judge Lead Judge about 1 hour ago
Submission Judgement Published
Validated
Assigned finding tags:

[H-01] After the user calls the `likeUser` function, the userBalance does not increase by the corresponding value.

## Description User A calls `likeUser` and sends `value > 1` ETH. According to the design of DatingDapp, the amount for user A should be accumulated by `userBalances`. Otherwise, in the subsequent calculations, the balance for each user will be 0. ## Vulnerability Details When User A calls `likeUser`, the accumulation of `userBalances` is not performed. ```solidity function likeUser( address liked ) external payable { require(msg.value >= 1 ether, "Must send at least 1 ETH"); require(!likes[msg.sender][liked], "Already liked"); require(msg.sender != liked, "Cannot like yourself"); require(profileNFT.profileToToken(msg.sender) != 0, "Must have a profile NFT"); require(profileNFT.profileToToken(liked) != 0, "Liked user must have a profile NFT"); likes[msg.sender][liked] = true; emit Liked(msg.sender, liked); // Check if mutual like if (likes[liked][msg.sender]) { matches[msg.sender].push(liked); matches[liked].push(msg.sender); emit Matched(msg.sender, liked); matchRewards(liked, msg.sender); } } ``` This will result in `totalRewards` always being 0, affecting all subsequent calculations: ```solidity uint256 totalRewards = matchUserOne + matchUserTwo; uint256 matchingFees = (totalRewards * FIXEDFEE ) / 100; uint256 rewards = totalRewards - matchingFees; totalFees += matchingFees; ``` ## POC ```solidity function testUserBalanceshouldIncreaseAfterLike() public { vm.prank(user1); likeRegistry.likeUser{value: 20 ether}(user2); assertEq(likeRegistry.userBalances(user1), 20 ether, "User1 balance should be 20 ether"); } ``` Then we will get an error: ```shell [FAIL: User1 balance should be 20 ether: 0 != 20000000000000000000] ``` ## Impact - Users will be unable to receive rewards. - The contract owner will also be unable to withdraw ETH from the contract. ## Recommendations Add processing for `userBalances` in the `likeUser` function: ```diff function likeUser( address liked ) external payable { require(msg.value >= 1 ether, "Must send at least 1 ETH"); require(!likes[msg.sender][liked], "Already liked"); require(msg.sender != liked, "Cannot like yourself"); require(profileNFT.profileToToken(msg.sender) != 0, "Must have a profile NFT"); require(profileNFT.profileToToken(liked) != 0, "Liked user must have a profile NFT"); likes[msg.sender][liked] = true; + userBalances[msg.sender] += msg.value; emit Liked(msg.sender, liked); [...] } ```

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