Prepared by:
HALBORN
Last Updated 12/26/2025
Date of Engagement: December 3rd, 2025 - December 9th, 2025
100% of all REPORTED Findings have been addressed
All findings
10
Critical
0
High
0
Medium
4
Low
2
Informational
4
ZKPass engaged Halborn to perform a security assessment of their smart contracts starting on December 3rd, 2025 and ending on December 8th, 2025. The assessment scope was limited to the smart contracts provided to Halborn. Commit hashes and additional details are available in the Scope section of this report.
The NodeStakingVault and StakingRewards contracts together implement a non-custodial staking, delegation, and reward-distribution system. Users can stake tokens, delegate to nodes, manage lockups and cooldowns, and earn rewards calculated based on effective stake, APY, and multipliers. The Vault handles delegation lifecycle and lockup enforcement, while StakingRewards manages on-chain reward accrual and claims.
Halborn was allocated 4 days for this engagement and assigned 1 full-time security engineers to conduct a comprehensive review of the smart contracts within scope. The engineers are experts in blockchain and smart contract security, with advanced skills in penetration testing and smart contract exploitation, as well as extensive knowledge of multiple blockchain protocols.
The objectives of this assessment are to:
Identify potential security vulnerabilities within the smart contracts.
Verify that the smart contract functionality operates as intended.
In summary, Halborn identified several areas for improvement to reduce the likelihood and impact of security risks, which were mostly addressed by the ZKPass team. The main recommendations were:
Add node activation checks to all increase functions.
Cap or reject any lockup extension that results in a total lockup exceeding MAXIMUM_USER_DELEGATE_LOCKUP_DURATION.
Update the MAX_BONUS constant in the contract to align with the documented behavior.
Implement a mechanism where initiating any unstake begins cooldown for all staked tokens.
Halborn conducted a combination of manual code review and automated security testing to balance efficiency, timeliness, practicality, and accuracy within the scope of this assessment. While manual testing is crucial for identifying flaws in logic, processes, and implementation, automated testing enhances coverage of smart contracts and quickly detects deviations from established security best practices.
The following phases and associated tools were employed throughout the term of the assessment:
Research into the platform's architecture, purpose and use.
Manual code review and walkthrough of smart contracts to identify any logical issues.
Comprehensive assessment of the safety and usage of critical Solidity variables and functions within scope that could lead to arithmetic-related vulnerabilities.
Local testing using custom scripts (Foundry).
Fork testing against main networks (Foundry).
Static security analysis of scoped contracts, and imported functions (Slither).
| EXPLOITABILITY METRIC () | METRIC VALUE | NUMERICAL VALUE |
|---|---|---|
| Attack Origin (AO) | Arbitrary (AO:A) Specific (AO:S) | 1 0.2 |
| Attack Cost (AC) | Low (AC:L) Medium (AC:M) High (AC:H) | 1 0.67 0.33 |
| Attack Complexity (AX) | Low (AX:L) Medium (AX:M) High (AX:H) | 1 0.67 0.33 |
| IMPACT METRIC () | METRIC VALUE | NUMERICAL VALUE |
|---|---|---|
| Confidentiality (C) | None (C:N) Low (C:L) Medium (C:M) High (C:H) Critical (C:C) | 0 0.25 0.5 0.75 1 |
| Integrity (I) | None (I:N) Low (I:L) Medium (I:M) High (I:H) Critical (I:C) | 0 0.25 0.5 0.75 1 |
| Availability (A) | None (A:N) Low (A:L) Medium (A:M) High (A:H) Critical (A:C) | 0 0.25 0.5 0.75 1 |
| Deposit (D) | None (D:N) Low (D:L) Medium (D:M) High (D:H) Critical (D:C) | 0 0.25 0.5 0.75 1 |
| Yield (Y) | None (Y:N) Low (Y:L) Medium (Y:M) High (Y:H) Critical (Y:C) | 0 0.25 0.5 0.75 1 |
| SEVERITY COEFFICIENT () | COEFFICIENT VALUE | NUMERICAL VALUE |
|---|---|---|
| Reversibility () | None (R:N) Partial (R:P) Full (R:F) | 1 0.5 0.25 |
| Scope () | Changed (S:C) Unchanged (S:U) | 1.25 1 |
| Severity | Score Value Range |
|---|---|
| Critical | 9 - 10 |
| High | 7 - 8.9 |
| Medium | 4.5 - 6.9 |
| Low | 2 - 4.4 |
| Informational | 0 - 1.9 |
Critical
0
High
0
Medium
4
Low
2
Informational
4
| Security analysis | Risk level | Remediation Date |
|---|---|---|
| Missing Node Activation Check in increaseDelegateAmount Allows Delegation to Deactivated Nodes | Medium | Solved - 12/21/2025 |
| Lockup Extension via increaseDelegateLockup() Breaks Maximum Lockup Invariant | Medium | Solved - 12/21/2025 |
| Incorrect MAX_BONUS Constant Causes 6x Multiplier Instead of 1.5x | Medium | Solved - 12/22/2025 |
| Users Can Exploit Cooldown Period to Earn Extra Rewards by Delaying Second initiateDelegateUnstake Call | Medium | Solved - 12/21/2025 |
| Users Can Accidentally Reset Cooldown Period by Calling initiateDelegateUnstake Instead of unstake | Low | Solved - 12/21/2025 |
| Missing Maximum Lockup Duration Check in increaseDelegateLockup | Low | Solved - 12/21/2025 |
| Unused onlySlasher Modifier and Unused penaltyTreasury Setter | Informational | Acknowledged - 12/22/2025 |
| Redundant Minimum Stake Duration Check in Unstake Logic | Informational | Solved - 12/21/2025 |
| Incorrect Error Message | Informational | Solved - 12/21/2025 |
| Centralization Risk | Informational | Acknowledged - 12/22/2025 |
//Medium
//Medium
//Medium
//Medium
//Low
//Low
//Informational
//Informational
//Informational
//Informational
Halborn strongly recommends conducting a follow-up assessment of the project either within six months or immediately following any material changes to the codebase, whichever comes first. This approach is crucial for maintaining the project’s integrity and addressing potential vulnerabilities introduced by code modifications.
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zkPass Node Vault Contracts
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