Managed Smart Contract Assessment

Summary#

XMAQUINA team engaged Halborn to conduct a security assessment on their smart contracts beginning on September 15th 2026 and ending on September 21st, 2026. 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 reviewed contracts form the RCM Protocol, which runs regulated primary issuance of tokenised notes against SPV interests on Base: KYC-verified investors subscribe USDC to an offering series, receive CMTAT-based notes once the underlying is acquired, and redeem them pro rata at a declared liquidity event. One escrow and one note deploy per series as a mutually pointing pair, and three fleet-wide singletons handle deployment, eligibility and disclosure. The escrow holds two liability pools, a subscription refund pool and a redemption payout pool, against a single USDC balance, and keeping those pools from drawing on each other is the design's own stated point of greatest concern. Operational roles sit under one role-admin key with the upgrader kept under the default admin, the singletons are UUPS proxies and the series pair sits behind two beacons with no timelock, and the repository carries a team-maintained register of accepted residuals and known issues that was validated in this assessment and is not re-reported here.

ASSESSMENT SUMMARY#

Halborn was provided with 5 days for this engagement and assigned 1 full-time security engineer to assess the security of the smart contracts in scope. The assigned engineer possesses deep expertise in blockchain and smart contract security, including hands-on experience with multiple blockchain protocols.

The objective of this assessment is 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 partially addressed by the XMAQUINA team. The main recommendations were:

• Require every eligibility write to carry an expiry set ahead of the current time, and require any reinstatement following a revocation to carry a fresh expiry so that a new review is visible on-chain.

• Reject conversion to oversubscribed mode when any recorded deposit falls below the new pro-rata floor.

• Bound each terminal refund to the balance not already owed to other subscribers so that the excess reserve remains covered after a swept series is cancelled

Scope#