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

Incorrect Claim Logic Implemented

ishwar

Description

  • Normally, any player except the current king should be able to claim the throne by paying the current claim fee. The claim logic is the fundamental gatekeeper for game progression.

  • Instead, the code only allows the current king to reclaim the throne. This mistake effectively locks the game, preventing new players from participating. The business logic is inverted, and the game cannot progress past the initial claim.

function claimThrone() external payable gameNotEnded nonReentrant {
require(msg.value >= claimFee, "Game: Insufficient ETH sent to claim the throne.");
@> require(msg.sender == currentKing, "Game: You are already the king. No need to re-claim."); <@
// rest of function
}

Risk

Likelihood:

  • This bug is always present (every claim attempt by a non-king will fail).

  • No player except the current king can ever claim the throne after deployment.

Impact:

  • The game is rendered non-functional after the first claim.

  • No new rounds, no competition, and no pot growth occurs.

Proof of Concept

// Only currentKing can claim, non-kings are blocked:
require(msg.sender == currentKing, "Game: You are already the king. No need to re-claim.");

Explanation:
Anyone except the current king will hit this require and revert, blocking all new claimants. This directly contradicts the business logic and makes the game unplayable beyond the first claim.

Recommended Mitigation

- require(msg.sender == currentKing, "Game: You are already the king. No need to re-claim.");
+ require(msg.sender != currentKing, "Game: You are already the king. No need to re-claim.");

Mitigation Explanation:
By changing the comparison to !=, only non-kings can claim, aligning with the intended game flow and restoring functionality.

Updates

Appeal created

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

Game::claimThrone `msg.sender == currentKing` check is busted

Support

FAQs

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