Impacts: Griefing (no profit motive required — attacker can harm other users or protocol)
Description
Brief / Intro
The staking contract uses the standard ERC-4626 vault implementation and relies on the default _decimalsOffset value. This enables an attack where the first staker can grief later stakers, causing them to receive zero (or fewer) shares for their deposits and suffer loss of funds.
Vulnerability Details
The contract uses a standard ERC-4626 vault which normally prevents many inflation attacks. However, because the default _decimalsOffset is used, the vault becomes vulnerable to a grieving / inflation-style attack where a malicious first staker manipulates the asset-to-share ratio to harm subsequent stakers.
The attack flow is described below.
1
Setup: attacker becomes first depositor
Attacker back-runs the pool creation transaction (or otherwise ensures they are the first depositor).
Attacker deposits a minimal amount to receive 1 share: deposit(1). Now totalAssets() == 1 and totalSupply() == 1.
2
Victim attempts to deposit
A victim attempts to deposit a larger amount (e.g., 50e18).
3
Attacker inflates asset balance
Attacker front-runs the victim's deposit and directly transfers a large amount of assets into the vault (e.g., asset.transfer(100e18) to the vault).
This artificially inflates totalAssets() while totalSupply() remains low (1), increasing the asset-per-share price.
4
Victim's deposit mints zero shares
The victim's deposit executes after the direct transfer inflation.
Due to the inflated asset-per-share ratio, the victim receives zero (or significantly fewer) shares for their deposit.
5
Attacker redeems inflated value
After any lock/unlock period, the attacker redeems their minimal share(s) and receives a large portion of the assets — these assets include amounts the attacker used to inflate the vault and the victim’s deposit, effectively causing the victim to lose funds.
6
Repetition / chaining
The attacker can repeat the same technique for subsequent stakers by directing transfers to the vault right before their deposits, causing partial or total loss for innocent stakers.
Impact Details
Total or partial loss of funds for honest stakers; attacker can grief other stakers without needing a profit motive (though profit can be extracted as described).
