Last Man Standing
First Flight #45
Beginner FriendlyFoundrySolidity
100 EXP
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Submission Details
Severity: medium
Valid

Missing Payout to Previous King

teejay4life

Root + Impact

Missing Payout to Previous King in claimThrone

Description

  • In the game, when a new player claims the throne, the previous king should receive a portion of the new claim fee as an incentive for holding the throne

  • However, in the current implementation, although the previousKingPayout variable exists, it is never assigned a value or transferred. As a result, the entire claim fee only funds the platform and the pot — the previous king never gets paid

function claimThrone() external payable gameNotEnded nonReentrant {
.
.
.
uint256 previousKingPayout = 0;
// @> This variable is never updated or paid out
.
.
.
}

Risk

Likelihood:

  • This happens every time any new player claims the throne while a previous king exists

  • It is guaranteed to happen because the logic to assign and transfer the payout is entirely missing

Impact:

  • Previous kings are never rewarded, breaking the core game incentive

  • This undermines user trust and the economic loop, since players pay to claim the throne but get no payout for being dethroned.

  • The entire ETH intended for payouts accumulates unfairly in the pot or platform fee.

Proof of Concept

  1. A player claims the throne and becomes king

  2. A new player becomes king but the previous king isn't paid for being the previous king

function test_claimThroneDoesNotPayPrevKing() public {
vm.startPrank(player1);
uint256 claimFee = game.claimFee(); // Ensure player1 sends enough ETH to cover the claim fee
​
// Player 1 claims the throne
game.claimThrone{value: claimFee}();
assertEq(game.currentKing(), player1, "Player 1 should be the current king");
uint256 balBeforeNextPlayer = player1.balance;
​
vm.stopPrank();
​
vm.startPrank(player2);
​
// Player 2 claims the throne
game.claimThrone{value: claimFee + 0.01 ether}();
uint256 balAfterNextPlayer = player1.balance;
assertEq(game.currentKing(), player2, "Player 2 should be the current king");
assertEq(balAfterNextPlayer, balBeforeNextPlayer, "Player 1 should not receive any ETH from Player 2");
​
vm.stopPrank();
}

Recommended Mitigation

Add a proper payout percentage for the dethroned king, ensure it is subtracted from the total amount, and securely transfer it

Updates

Appeal created

inallhonesty Lead Judge 14 days ago
Submission Judgement Published
Validated
Assigned finding tags:

Missing Previous King Payout Functionality

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