Prepared by:
HALBORN
Last Updated 11/14/2025
Date of Engagement: October 10th, 2025 - October 20th, 2025
100% of all REPORTED Findings have been addressed
All findings
15
Critical
0
High
0
Medium
3
Low
7
Informational
5
TeaFi engaged Halborn to conduct a security assessment on their smart contracts beginning on October 10, 2025 and ending on October 20, 2025. The scope of this assessment was limited to the smart contracts provided to the Halborn team. Commit hashes and additional details are documented in the Scope section of this report.
TeaFi's Noga Fallback contract's are a modular smart contract system built on the Diamond Standard (EIP‑2535) for secure, gasless ERC‑20 token swaps and transfers. It features upgradeable facets for admin control, whitelisting, and execution, with strict role-based access and slippage protection. Using Permit2 and other permit standards, relayers can perform authorized actions on behalf of users. The system includes treasury-based fee collection, pausability, emergency withdrawals, and safeguards like whitelisted function selectors and reentrancy protection.
Halborn was provided 7 days for the engagement and assigned 1 full-time security engineer to review the security of the smart contracts in scope. The engineer is a blockchain and smart contract security expert with advanced penetration testing and smart contract hacking skills, and deep knowledge of multiple blockchain protocols.
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 several areas for improvement to reduce both the likelihood and impact of potential risks, which were mostly addressed by the TeaFi team. The primary suggestions included:
Modify LibPermit.makeTokenPermit() to check if the current allowance is already sufficient for the transfer amount.
Extract and validate the amountOutMin from callData to ensure it matches.
Implement pre-execution allowance validation before other operations and nonce consumption.
Measure the actual amount received after transfer and use that for refunds.
Remove the msg.value check inside _validateCall().
Remove the unnecessary BaseFacet inheritance from DiamondCutFacet.
Halborn performed a combination of manual code review and automated security testing to balance efficiency, timeliness, practicality, and accuracy in regard to the scope of this assessment. While manual testing is essential to uncover flaws in logic, process, and implementation, automated testing techniques enhance coverage of smart contracts and can quickly identify issues that do not follow security best practices.
The following phases and associated tools were used throughout the assessment:
Research into the architecture, purpose, and use of the platform.
Manual code review and walkthrough of the smart contracts to identify potential logic issues.
Manual testing of all core functions, including createCampaign, claim to validate expected behavior and identify edge-case vulnerabilities.
Local testing to simulate contract interactions and validate functional and security assumptions.
Local deployment and testing with Foundry.
| 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
3
Low
7
Informational
5
| Security analysis | Risk level | Remediation Date |
|---|---|---|
| Front-Running Permit Signatures Causes Transaction Reversion | Medium | Solved - 11/10/2025 |
| Griefing Attack via Zero Allowance Causing Relayer Gas Loss | Medium | Solved - 11/10/2025 |
| Fee-on-Transfer Token Handling Causes Refund Failures or User Profit from Contract Balance | Medium | Solved - 11/10/2025 |
| Users Can Grief Relayers by Providing Mismatched Slippage Parameters | Low | Risk Accepted - 11/11/2025 |
| Unused Admin Parameter in DiamondInit Initialization | Low | Solved - 11/10/2025 |
| Redundant permit2 Initialization in Diamond Deployment | Low | Solved - 11/10/2025 |
| Lack of Emergency Role or Protocol Pause Check for Emergency Withdrawals | Low | Solved - 11/10/2025 |
| Unnecessary BaseFacet Inheritance in DiamondCutFacet | Low | Solved - 11/10/2025 |
| Unnecessary msg.value > 0 Check in _validateCall() | Low | Solved - 11/10/2025 |
| Missing Interface Registrations in DiamondInit Breaks ERC-165 Compliance | Low | Solved - 11/10/2025 |
| EmergencyWithdrawErc20 Emits Token Addresses Even When No Tokens Are Withdrawn | Informational | Solved - 11/10/2025 |
| setTreasury() Allows Setting the Same Treasury Address Repeatedly | Informational | Solved - 11/10/2025 |
| Gas Inefficiency Due to Late Zero Address Check | Informational | Solved - 11/10/2025 |
| Missing unchecked Block in replaceFunctions() Selector Loo | Informational | Solved - 11/10/2025 |
| Unused Custom Errors | Informational | Solved - 11/10/2025 |
//Medium
//Medium
//Medium
//Low
//Low
//Low
//Low
//Low
//Low
//Low
//Informational
//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.
// Download the full report
Noga Fallback Contracts
* Use Google Chrome for best results
** Check "Background Graphics" in the print settings if needed
