51713 sc low missing minimum stake validation in unstake operations

Submitted on Aug 5th 2025 at 08:11:58 UTC by @rilwan99 for Attackathon | Plume Network

• Report ID: #51713

• Report Type: Smart Contract

• Report severity: Low

• Target: https://github.com/immunefi-team/attackathon-plume-network/blob/main/plume/src/facets/StakingFacet.sol

• Impacts:

  • Contract fails to deliver promised returns, but doesn't lose value

Description

Brief/Intro

The PlumeStaking contract allows users to perform partial unstaking without validating that the remaining stake meets the minStakeAmount requirement. This creates dust stakes below the minimum threshold and a loophole for users to bypass the minimum stake amount restriction.

Vulnerability Details

The unstake() function validates the unstake amount but fails to check if the remaining stake meets minimum requirements:

function _unstake(uint16 validatorId, uint256 amount) internal returns (uint256 amountToUnstake) {
    // Validates unstake amount only
    _validateValidatorForUnstaking(validatorId);
    if (amount == 0) {
        revert InvalidAmount(amount);
    }
    if ($s.userValidatorStakes[msg.sender][validatorId].staked < amount) {
        revert InsufficientFunds($s.userValidatorStakes[msg.sender][validatorId].staked, amount);
    }
    // Missing: validation of remaining stake amount
}

This vulnerability is also present in restake(), as the restake() function moves funds from cooldown/parked to active stake on a different validator without ensuring the source validator retains minimum stake:

function restake(uint16 validatorId, uint256 amount) external nonReentrant {
    // ... validation logic
    _performStakeSetup(user, validatorId, amount); // Only validates new stake amount
    // Missing: validation that source validator stake remains above minimum
}

Impact Details

Economic Impact

• Gas Inefficiency: Dust stakes increase gas costs for yield distribution operations as the system must process many sub-minimum positions

• Validator Overhead: Validators experience increased operational costs managing numerous small stakes

• System Degradation: Accumulation of dust positions leads to bloated storage and reduced performance

Severity

This is a MEDIUM severity issue as it:

• Causes significant system inefficiency and poor user experience

• Creates technical debt that compounds over time

• Affects core staking mechanics used by all participants

References

Add any relevant links to documentation or code

Proof of Concept

1

Dust Stakes via Partial Unstaking

Setup:

• User stakes 100 PLUME with Validator A, minStakeAmount = 10 PLUME

Action:

• User calls unstake(validatorA, 95) to unstake 95 PLUME

Validation:

• Function validates 95 PLUME > minStakeAmount ✓

Result:

• 5 PLUME remains staked (below 10 PLUME minimum)

Impact:

• User has economically unviable dust stake position

2

Dust Stakes via Restaking

Setup:

• User has 100 PLUME staked with Validator A, 50 PLUME in cooldown

Action:

• User calls restake(validatorB, 95)

Validation:

• Function validates 95 PLUME restake amount ✓

Execution:

• 50 PLUME from cooldown + 45 PLUME from Validator A stake moved to Validator B

Result:

• 5 PLUME remains with Validator A (below minimum)

Impact:

• User now has fragmented positions with dust stake