MyCut

AI First Flight #8
Beginner FriendlyFoundry
EXP
View results
Submission Details
Severity: high
Valid

When zero players claim, 90% of all deposited funds are permanently locked after closePot()

Root + Impact

Description

If no player calls claimCut() before the 90-day window expires, claimants is an empty array. closePot() correctly pays the 10% manager cut, then enters a loop over claimants — which is a no-op. The remaining 90% of remainingRewards stays in the Pot forever. There is no follow-up withdrawal, re-open, or emergency-sweep mechanism.

// Pot.sol :: closePot()
if (remainingRewards > 0) {
uint256 managerCut = remainingRewards / managerCutPercent;
i_token.transfer(msg.sender, managerCut); // ✓ manager receives 10%
uint256 claimantCut = (remainingRewards - managerCut) / i_players.length;
// @> claimants is empty — this loop executes zero times
for (uint256 i = 0; i < claimants.length; i++) {
_transferReward(claimants[i], claimantCut);
}
// @> 90% of remainingRewards is now unrecoverable
}

Risk

Likelihood:

  • A contest created for a cancelled event, a contest whose player list has entirely cold wallets, or a deliberate griefing scenario (no one claims to force the lock) all lead to this state.

  • The 90-day timer is absolute — once it expires and closePot() is called, the state is final.

Impact:

  • 90% of all tokens deposited into the Pot are permanently inaccessible to any party.

  • The manager loses the distributable share; token holders lose their assets; the protocol loses credibility.

Proof of Concept

// Deploy Pot with 5 players, totalRewards = 10_000e6 (USDC)
// Nobody calls claimCut() for 90 days
// Owner calls closeContest(potAddress)
// Execution:
// managerCut = 10_000e6 / 10 = 1_000e6 → transferred to owner
// claimantCut = 9_000e6 / 5 = 1_800e6
// loop: 0 iterations (claimants.length == 0)
// Result:
// Owner received : 1_000e6 USDC
// Pot balance : 9_000e6 USDC ← locked forever

Recommended Mitigation

+ // Add at the top of the if-block, before computing cuts:
+ if (claimants.length == 0) {
+ i_token.safeTransfer(msg.sender, remainingRewards);
+ remainingRewards = 0;
+ return;
+ }
uint256 managerCut = remainingRewards / managerCutPercent;
// ... rest unchanged
Updates

Lead Judging Commences

ai-first-flight-judge Lead Judge 2 days ago
Submission Judgement Published
Validated
Assigned finding tags:

[H-02] Incorrect logic in `Pot::closePot` leads to unfair distribution to `claimants`, potentially locking the funds with no way to take that out

## Description in `closePot` function while calclulating the shares for claimaint cut, `i_players.length` is used, instead of `claimants.length`, causing low amount being distributed to claimants. ## Vulnerability Details [2024-08-MyCut/src/Pot.sol at main · Cyfrin/2024-08-MyCut (github.com)](https://github.com/Cyfrin/2024-08-MyCut/blob/main/src/Pot.sol#L57) `Pot::closePot` function is meant to be called once contest passed 90 days, it sends the owner cut to owner and rest is splitted among the users who claimed b/w 90 days period. However, current implementation is wrong.&#x20; It uses total users (i_players.length) instead of the users (claimants.length) who claimed during the duration. This creates an unfair distribution to the participants and some of the funds could be locked in the contract. In worst case scenerio, it could be 90% if nobody has claimed from the protocol during the 90 days duration. ## POC In existing test suite, add following test: ```solidity function testUnfairDistributionInClosePot() public mintAndApproveTokens { // Setup address[] memory testPlayers = new address[](3); testPlayers[0] = makeAddr("player1"); testPlayers[1] = makeAddr("player2"); testPlayers[2] = makeAddr("player3"); uint256[] memory testRewards = new uint256[](3); testRewards[0] = 400; testRewards[1] = 300; testRewards[2] = 300; uint256 testTotalRewards = 1000; // Create and fund the contest vm.startPrank(user); address testContest = ContestManager(conMan).createContest( testPlayers, testRewards, IERC20(ERC20Mock(weth)), testTotalRewards ); ContestManager(conMan).fundContest(0); vm.stopPrank(); // Only player1 claims their reward vm.prank(testPlayers[0]); Pot(testContest).claimCut(); // Fast forward 91 days vm.warp(block.timestamp + 91 days); // Record balances before closing the pot uint256 player1BalanceBefore = ERC20Mock(weth).balanceOf( testPlayers[0] ); // Close the contest vm.prank(user); ContestManager(conMan).closeContest(testContest); // Check balances after closing the pot uint256 player1BalanceAfter = ERC20Mock(weth).balanceOf(testPlayers[0]); // Calculate expected distributions uint256 remainingRewards = 600; // 300 + 300 unclaimed rewards uint256 ownerCut = remainingRewards / 10; // 10% of remaining rewards uint256 distributionPerPlayer = (remainingRewards - ownerCut) / 1; // as only 1 user claimed uint256 fundStucked = ERC20Mock(weth).balanceOf(address(testContest)); // actual results console.log("expected reward:", distributionPerPlayer); console.log( "actual reward:", player1BalanceAfter - player1BalanceBefore ); console.log("Fund stucked:", fundStucked); } ``` then run `forge test --mt testUnfairDistributionInClosePot -vv` in the terminal and it will show following output: ```js [⠊] Compiling... [⠒] Compiling 1 files with Solc 0.8.20 [⠘] Solc 0.8.20 finished in 1.63s Compiler run successful! Ran 1 test for test/TestMyCut.t.sol:TestMyCut [PASS] testUnfairDistributionInClosePot() (gas: 905951) Logs: User Address: 0x6CA6d1e2D5347Bfab1d91e883F1915560e09129D Contest Manager Address 1: 0x7BD1119CEC127eeCDBa5DCA7d1Bd59986f6d7353 Minting tokens to: 0x6CA6d1e2D5347Bfab1d91e883F1915560e09129D Approved tokens to: 0x7BD1119CEC127eeCDBa5DCA7d1Bd59986f6d7353 expected reward: 540 actual reward: 180 Fund stucked: 360 Suite result: ok. 1 passed; 0 failed; 0 skipped; finished in 1.58ms (506.33µs CPU time) ``` ## Impact Loss of funds, Unfair distribution b/w users ## Recommendations Fix the functions as shown below: ```diff function closePot() external onlyOwner { if (block.timestamp - i_deployedAt < 90 days) { revert Pot__StillOpenForClaim(); } if (remainingRewards > 0) { uint256 managerCut = remainingRewards / managerCutPercent; i_token.transfer(msg.sender, managerCut); - uint256 claimantCut = (remainingRewards - managerCut) / i_players.length; + uint256 totalClaimants = claimants.length; + if(totalClaimant == 0){ + _transferReward(msg.sender, remainingRewards - managerCut); + } else { + uint256 claimantCut = (remainingRewards - managerCut) / claimants.length; for (uint256 i = 0; i < claimants.length; i++) { _transferReward(claimants[i], claimantCut); } } + } } ```

Support

FAQs

Can't find an answer? Chat with us on Discord, Twitter or Linkedin.

Give us feedback!