Prepared by:
HALBORN
Last Updated 07/15/2025
Date of Engagement: May 26th, 2025 - June 2nd, 2025
100% of all REPORTED Findings have been addressed
All findings
3
Critical
0
High
0
Medium
1
Low
0
Informational
2
Caldera engaged Halborn to conduct a security assessment on their smart contracts beginning on May 26th, 2025 and ending on June 2nd, 2025. The security assessment was scoped to the smart contracts provided to Halborn. Commit hashes and further details can be found in the Scope section of this report.
The Caldera codebase in scope consists of the MetaERC20 smart contracts, a cross-chain token bridge built on top of the Metalayer/Hyperlane messaging protocol. It enables seamless transfer of ERC20 tokens between different blockchain networks while maintaining token supply integrity and providing security controls for high-value transfers.
Halborn was provided 7 days for the engagement and assigned a full-time security engineer to review the security of the smart contracts in scope.
The purpose of the assessment is to:
Identify potential security issues within the smart contracts.
Ensure that smart contract functionality operates as intended.
In summary, Halborn identified some improvements to reduce the likelihood and impact of risks, which were completely addressed by Caldera. The main one was the following:
Implement a functionality to disallow transfers marked as executed during emergency to be executed again
Halborn performed a manual review of the code. Manual testing is great to uncover flaws in logic, process, and implementation.
The following phases and associated tools were used throughout the term of the assessment:
Research into architecture, purpose and use of the platform.
Smart contract manual code review and walkthrough to identify any logic issue.
Thorough assessment of safety and usage of critical Solidity variables and functions in scope that could led to arithmetic related vulnerabilities.
| 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
1
Low
0
Informational
2
| Security analysis | Risk level | Remediation Date |
|---|---|---|
| Emergency functions do not consider a possible message arrival in the future | Medium | Solved - 05/28/2025 |
| Floating pragma version | Informational | Solved - 07/08/2025 |
| Redundant checks in token recovery functions | Informational | Solved - 07/08/2025 |
//Medium
//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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Metalayer-Fetcher: Smart Contract Assessment
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