We express our gratitude to the Cradle team for the collaborative engagement that enabled the execution of this Smart Contract Security Assessment.
VestedAirdrop - is a contract that facilitates token distribution using a vesting mechanism with Merkle tree validation.
Document
Review Scope
The system users should acknowledge all the risks summed up in the risks section of the report.
Functional requirements are not provided.
Technical description is not provided.
The code mostly follows best practices.
The development environment is not configured.
Code coverage of the project is 0% (branch coverage).
Tests were not provided.
VestedAirdrop - is a contract that facilitates token distribution using a vesting mechanism with Merkle tree validation. It enables eligible users to claim tokens based on a vesting schedule, which includes an initial release of 31% (TGE) and linear vesting of the remaining 69% over a specified period. The contract ensures secure token distribution, tracks claimed amounts to prevent over-claiming and allows the owner to update the Merkle root or rescue unclaimed tokens
The owner of the VestedAirdrop contract can update the Merkle root, and rescue unclaimed tokens.
Owner's Unrestricted State Modification: The absence of restrictions on state variable modifications by the owner leads to arbitrary changes, affecting contract integrity and user trust, especially during critical operations like minting phases.
Code ― | Title | Status | Severity | |
---|---|---|---|---|
F-2025-8526 | Events Missing Indexed Parameters | Fixed | Observation | |
F-2025-8524 | Missing Zero Address Validation | Accepted | Observation |
When auditing smart contracts, Hacken is using a risk-based approach that considers Likelihood, Impact, Exploitability and Complexity metrics to evaluate findings and score severities.
Reference on how risk scoring is done is available through the repository in our Github organization:
Severity
Description
Severity
Description
Severity
Description
Severity
Description
The "Potential Risks" section identifies issues that are not direct security vulnerabilities but could still affect the project’s performance, reliability, or user trust. These risks arise from design choices, architectural decisions, or operational practices that, while not immediately exploitable, may lead to problems under certain conditions. Additionally, potential risks can impact the quality of the audit itself, as they may involve external factors or components beyond the scope of the audit, leading to incomplete assessments or oversight of key areas. This section aims to provide a broader perspective on factors that could affect the project's long-term security, functionality, and the comprehensiveness of the audit findings.
The scope of the project includes the following smart contracts from the provided repository:
Scope Details
VestedAidrop.vy
During the audit of Cradle, Hacken followed its methodology by performing fuzz-testing on the project's main functions. Foundry, a tool used for fuzz-testing, was employed to check how the protocol behaves under various inputs. Due to the complex and dynamic interactions within the protocol, unexpected edge cases might arise. Therefore, it was important to use fuzz-testing to ensure that several system invariants hold true in all situations.
Fuzz-testing allows the input of many random data points into the system, helping to identify issues that regular testing might miss. A specific Echidna fuzzing suite was prepared for this task, and throughout the assessment, 9 invariants were tested over 100,000 runs. This thorough testing ensured that the system works correctly even with unexpected or unusual inputs.
Invariant
Test Result
Run Count
Invariant
claimed_amount
of a user must increase only when a valid claim
is processed.Test Result
Run Count
Invariant
merkle_root
must only be updated by the contract owner.Test Result
Run Count
Invariant
rescue_tokens
function.Test Result
Run Count
Invariant
rescue_tokens
function must reduce the contract's token balance by the specified amount.Test Result
Run Count
Invariant
claim
function must revert if the proof
is invalid.Test Result
Run Count
Invariant
claim
function must revert if the current time is before the vesting_start_time
.Test Result
Run Count
Invariant
31% TGE
and 69% linear vesting
formula.Test Result
Run Count
Invariant
vesting_end_time
, all tokens must be fully vested and claimable.Test Result
Run Count
The smart contracts in the scope of this audit could benefit from the introduction of automatic emergency actions for critical activities, such as unauthorized operations like ownership changes or proxy upgrades, as well as unexpected fund manipulations, including large withdrawals or minting events. Adding such mechanisms would enable the protocol to react automatically to unusual activity, ensuring that the contract remains secure and functions as intended.
To improve functionality, these emergency actions could be designed to trigger under specific conditions, such as:
Detecting changes to ownership or critical permissions.
Monitoring large or unexpected transactions and minting events.
Pausing operations when irregularities are identified.
These enhancements would provide an added layer of security, making the contract more robust and better equipped to handle unexpected situations while maintaining smooth operations.