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Superstate A-6

Security Audit

April 15th, 2025

Version 1.0.0

Presented by 0xMacro

Table of Contents

Introduction

This document includes the results of the security audit for Superstate's smart contract code as found in the section titled ‘Source Code’. The security audit was performed by the Macro security team on April 14th, 2025.

The purpose of this audit is to review the source code of certain Superstate Solidity contracts, and provide feedback on the design, architecture, and quality of the source code with an emphasis on validating the correctness and security of the software in its entirety.

Disclaimer: While Macro’s review is comprehensive and has surfaced some changes that should be made to the source code, this audit should not solely be relied upon for security, as no single audit is guaranteed to catch all possible bugs.

Overall Assessment

The following is an aggregation of issues found by the Macro Audit team:

Severity Count Acknowledged Won't Do Addressed
Code Quality 2 - - 2

Superstate was quick to respond to these issues.

Specification

Our understanding of the specification was based on the following sources:

Source Code

The following source code was reviewed during the audit:

Specifically, we audited the following contracts within these repositories:

Source Code SHA256
ustb/src/SuperstateToken.sol

3cc5b3ace0eeea34e30b7906a92f9cbc763cf19ebff75f9ebb2af70c97218908

ustb/src/interfaces/ISuperstateToken.sol

ddb4bf6ddc72f0d1b41c2363251643630dfa8a598e7d0a38e6de35116d15253b

onchain-redemptions/src/ISuperstateToken.sol

1fea5d532d733091401fb5d8d99fe7911cc3fc9dca795375350354a4fbeec2d8

onchain-redemptions/src/Redemption.sol

ab3e9f966829e6fae45579fa69a951d4c08fb64f80eb5073c3a62e766b3b06b1

onchain-redemptions/src/RedemptionIdle.sol

0c2dd1ff4a912eca4eac3ee196ab8351f5c9e353b9ec35a48f6c7b63eed474d9

onchain-redemptions/src/RedemptionYield.sol

e7f72c4646b9de81a31017ecf2587e80619ae4e2d01f4b9113033fbb0183c620

onchain-redemptions/src/interfaces/IRedemption.sol

345aa94afb137a8cc07e202d75ec56535b10157ba4a1d32c11badfe1f7bdb123

Note: This document contains an audit solely of the Solidity contracts listed above. Specifically, the audit pertains only to the contracts themselves, and does not pertain to any other programs or scripts, including deployment scripts.

Issue Descriptions and Recommendations

Click on an issue to jump to it, or scroll down to see them all.

Security Level Reference

We quantify issues in three parts:

  1. The high/medium/low/spec-breaking impact of the issue:
    • How bad things can get (for a vulnerability)
    • The significance of an improvement (for a code quality issue)
    • The amount of gas saved (for a gas optimization)
  2. The high/medium/low likelihood of the issue:
    • How likely is the issue to occur (for a vulnerability)
  3. The overall critical/high/medium/low severity of the issue.

This third part – the severity level – is a summary of how much consideration the client should give to fixing the issue. We assign severity according to the table of guidelines below:

Severity Description
(C-x)
Critical

We recommend the client must fix the issue, no matter what, because not fixing would mean significant funds/assets WILL be lost.

(H-x)
High

We recommend the client must address the issue, no matter what, because not fixing would be very bad, or some funds/assets will be lost, or the code’s behavior is against the provided spec.

(M-x)
Medium

We recommend the client to seriously consider fixing the issue, as the implications of not fixing the issue are severe enough to impact the project significantly, albiet not in an existential manner.

(L-x)
Low

The risk is small, unlikely, or may not relevant to the project in a meaningful way.

Whether or not the project wants to develop a fix is up to the goals and needs of the project.

(Q-x)
Code Quality

The issue identified does not pose any obvious risk, but fixing could improve overall code quality, on-chain composability, developer ergonomics, or even certain aspects of protocol design.

(I-x)
Informational

Warnings and things to keep in mind when operating the protocol. No immediate action required.

(G-x)
Gas Optimizations

The presented optimization suggestion would save an amount of gas significant enough, in our opinion, to be worth the development cost of implementing it.

Issue Details

Q-1

Missing function declaration in ISuperstateToken

Topic
Best practices
Status
Quality Impact
Low

In the ISuperstateToken interface defined in ustb repository, both subscribe function variants (with and without to address parameter) are missing.

Consider adding function declaration for these two functions.

Q-2

The ISuperstateToken interface in onchain-redemptions is not up-to-date

Topic
Best practice
Status
Quality Impact
Low

The ISuperstateToken interface file in onchain-redemptions has not been updated with the latest version of ISuperstateToken from the ustb repo. For example, it doesn't have the SubscribeV2 event.

Consider updating the interface file to contain only relevant functions and events, or keep it up to date with the latest version from the ustb repo.

Disclaimer

Macro makes no warranties, either express, implied, statutory, or otherwise, with respect to the services or deliverables provided in this report, and Macro specifically disclaims all implied warranties of merchantability, fitness for a particular purpose, noninfringement and those arising from a course of dealing, usage or trade with respect thereto, and all such warranties are hereby excluded to the fullest extent permitted by law.

Macro will not be liable for any lost profits, business, contracts, revenue, goodwill, production, anticipated savings, loss of data, or costs of procurement of substitute goods or services or for any claim or demand by any other party. In no event will Macro be liable for consequential, incidental, special, indirect, or exemplary damages arising out of this agreement or any work statement, however caused and (to the fullest extent permitted by law) under any theory of liability (including negligence), even if Macro has been advised of the possibility of such damages.

The scope of this report and review is limited to a review of only the code presented by the Superstate team and only the source code Macro notes as being within the scope of Macro’s review within this report. This report does not include an audit of the deployment scripts used to deploy the Solidity contracts in the repository corresponding to this audit. Specifically, for the avoidance of doubt, this report does not constitute investment advice, is not intended to be relied upon as investment advice, is not an endorsement of this project or team, and it is not a guarantee as to the absolute security of the project. In this report you may through hypertext or other computer links, gain access to websites operated by persons other than Macro. Such hyperlinks are provided for your reference and convenience only, and are the exclusive responsibility of such websites’ owners. You agree that Macro is not responsible for the content or operation of such websites, and that Macro shall have no liability to your or any other person or entity for the use of third party websites. Macro assumes no responsibility for the use of third party software and shall have no liability whatsoever to any person or entity for the accuracy or completeness of any outcome generated by such software.