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

Missing Previous King Payout Functionality

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