credit-facility Audit | NUVA | Halborn Audit Reports

Summary

100% of all REPORTED Findings have been addressed

About this report

Assessment Type

Assurance Assessment

Date of Engagement

September 29th, 2026 - October 1st, 2026

Source Code

vault-credit-facility

Assessed Commit ID

be55336

Severity Breakdown

0Solved
3Future Release
1Acknowledged
4All Findings

Critical0
High0
Medium0
Low0
Informational4
- 1Ack.
- 3F. Release

Introduction#

NUVA engaged Halborn to conduct a security assessment of the vault credit facility smart contracts on Provenance, beginning on September 29th, 2026, and concluding on October 1st, 2026. This security assessment was scoped to the in-scope Rust source of the vault-credit-facility-lite contract and the shared vault-settlement library. Commit hashes, audited components, and further details can be found in the Scope section of this report.

The lite facility is a minimal CosmWasm credit line that tracks par (1:1) debt between vault underlying and a receipt marker held in the vault. Draw and repay flows are planned through settlement helpers that emit Provenance vault, marker, and bank messages. The design must preserve ledger consistency, respect vault pause and halt semantics, and avoid unsafe forwarding of drawn funds.

Assessment Summary#

The team at Halborn assigned a full-time security engineer to verify the security of the smart contracts. The security engineer is a blockchain and smart-contract security expert with advanced penetration testing, smart-contract hacking, and deep knowledge of multiple blockchain protocols.

The purpose of this assessment is to:

Ensure that smart contract functions operate as intended
Identify potential security issues with the smart contracts

In summary, Halborn identified some improvements to reduce the likelihood and impact of risks, which have been acknowledged by the NUVA team. The main ones were the following:

Apply min(payment.amount, principal) to repayments and refund any excess underlying to the sender in the same transaction as settlement.
Add an admin-gated sweep that returns accidentally received native tokens to a validated recipient, rejecting attached funds and the contract itself as recipient.
Reject the contract address as destination, and verify that a fresh instance binds to an existing vault, matching underlying, and a receipt marker with zero supply before operational use.
Require principal, receipt supply, and vault receipt holdings to match before Draw changes state, and reject the draw when they differ without adjusting balances automatically.

Test Approach and Methodology#

Halborn performed a combination of manual and automated security testing to balance efficiency, timeliness, practicality, and accuracy in regard to the scope of this assessment. While manual testing is recommended to uncover flaws in logic, process, and implementation, automated testing techniques help enhance code coverage and quickly identify items that do not follow security best practices. The following phases and associated tools were used during the assessment:

Research into the lite facility architecture, and documented trust boundaries for admin, borrower, and permissionless entrypoints.
Manual review of in-scope CosmWasm entrypoints, storage layout, and message planners across the lite contract and settlement library.
Verification of role checks, halt gating, vault pause handling, and fund attachment rules on execute paths.
Analysis of draw, repay, and interest-deposit flows against par pricing, principal accounting, and reconciliation queries.
Evaluation of migration semantics, configuration validation, and liveness edge cases on queries and settlement reads.
Use of repository unit tests and harness-driven scenarios to support reachability analysis.

Risk Methodology#

Every vulnerability and issue observed by Halborn is ranked based on two sets of Metrics and a Severity Coefficient. This system is inspired by the industry standard Common Vulnerability Scoring System.

The two Metric sets are: Exploitability and Impact. Exploitability captures the ease and technical means by which vulnerabilities can be exploited and Impact describes the consequences of a successful exploit.

The Severity Coefficients is designed to further refine the accuracy of the ranking with two factors: Reversibility and Scope. These capture the impact of the vulnerability on the environment as well as the number of users and smart contracts affected.

The final score is a value between 0-10 rounded up to 1 decimal place and 10 corresponding to the highest security risk. This provides an objective and accurate rating of the severity of security vulnerabilities in smart contracts.

The system is designed to assist in identifying and prioritizing vulnerabilities based on their level of risk to address the most critical issues in a timely manner.

4.1 EXPLOITABILITY

Attack Origin (AO):

Captures whether the attack requires compromising a specific account.

Attack Cost (AC):

Captures the cost of exploiting the vulnerability incurred by the attacker relative to sending a single transaction on the relevant blockchain. Includes but is not limited to financial and computational cost.

Attack Complexity (AX):

Describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Includes but is not limited to macro situation, available third-party liquidity and regulatory challenges.

Metrics:

EXPLOITABILITY METRIC ( $m_e$ )	METRIC VALUE	NUMERICAL VALUE
Attack Origin (AO)	Arbitrary (AO:A)	1
Attack Origin (AO)	Specific (AO:S)	0.2
Attack Cost (AC)	Low (AC:L)	1
	Medium (AC:M)	0.67
	High (AC:H)	0.33
Attack Complexity (AX)	Low (AX:L)	1
	Medium (AX:M)	0.67
	High (AX:H)	0.33

Exploitability

E

is calculated using the following formula:

$E = \prod m_e$

4.2 IMPACT

Confidentiality (C):

Measures the impact to the confidentiality of the information resources managed by the contract due to a successfully exploited vulnerability. Confidentiality refers to limiting access to authorized users only.

Integrity (I):

Measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of data stored and/or processed on-chain. Integrity impact directly affecting Deposit or Yield records is excluded.

Availability (A):

Measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. This metric refers to smart contract features and functionality, not state. Availability impact directly affecting Deposit or Yield is excluded.

Deposit (D):

Measures the impact to the deposits made to the contract by either users or owners.

Yield (Y):

Measures the impact to the yield generated by the contract for either users or owners.

Metrics:

IMPACT METRIC ( $m_I$ )	METRIC VALUE	NUMERICAL VALUE
Confidentiality (C)	None (C:N)	0
	Low (C:L)	0.25
	Medium (C:M)	0.5
	High (C:H)	0.75
	Critical (C:C)	1
Integrity (I)	None (I:N)	0
	Low (I:L)	0.25
	Medium (I:M)	0.5
	High (I:H)	0.75
	Critical (I:C)	1
Availability (A)	None (A:N)	0
	Low (A:L)	0.25
	Medium (A:M)	0.5
	High (A:H)	0.75
	Critical (A:C)	1
Deposit (D)	None (D:N)	0
	Low (D:L)	0.25
	Medium (D:M)	0.5
	High (D:H)	0.75
	Critical (D:C)	1
Yield (Y)	None (Y:N)	0
	Low (Y:L)	0.25
	Medium (Y:M)	0.5
	High (Y:H)	0.75
	Critical (Y:C)	1

Impact

I

is calculated using the following formula:

$I = max(m_I) + \frac{\sum{m_I} - max(m_I)}{4}$

4.3 SEVERITY COEFFICIENT

Reversibility (R):

Describes the share of the exploited vulnerability effects that can be reversed. For upgradeable contracts, assume the contract private key is available.

Scope (S):

Captures whether a vulnerability in one vulnerable contract impacts resources in other contracts.

Metrics:

SEVERITY COEFFICIENT ( $C$ )	COEFFICIENT VALUE	NUMERICAL VALUE
Reversibility ( $r$ )	None (R:N)	1
	Partial (R:P)	0.5
	Full (R:F)	0.25
Scope ( $s$ )	Changed (S:C)	1.25
Scope ( $s$ )	Unchanged (S:U)	1

Severity Coefficient

C

is obtained by the following product:

$C = rs$

The Vulnerability Severity Score

S

is obtained by:

$S = min(10, EIC * 10)$

The score is rounded up to 1 decimal places.

Critical	High	Medium	Low	Informational
9 - 10	7 - 8.9	4.5 - 6.9	2 - 4.4	0 - 1.9

Scope#

(a) Repository:vault-credit-facility

(b) Assessed Commit ID:be55336105e28f440ee7be8418b5d62316b0058e

13 files

contracts

13 files

lite / src

7 files

contract.rs

rust

error.rs

rust

handlers.rs

rust

lib.rs

rust

msg.rs

rust

plan.rs

rust

state.rs

rust

settlement / src

6 files

error.rs

rust

lib.rs

rust

Out-of-Scope: New features/implementations after the remediation commit IDs.

Assessment Summary & Findings Overview#

#	Title	Severity	Score	Status
HAL-01	Repayments Exceeding Outstanding Principal Revert Instead of Refunding Excess	Informational	1.7	Acknowledged10/09/2026
HAL-02	Native Tokens Sent Outside the Intended Flows Have No Recovery Operation	Informational	1.0	Future Release10/09/2026
HAL-03	Configuration Validation Does Not Check Destination Suitability or Vault Bindings	Informational	1.0	Future Release10/09/2026
HAL-04	New Draws Are Not Gated on the Receipt Reconciliation Invariant	Informational	0.0	Future Release10/09/2026

Findings & Tech Details#

HAL-01Acknowledged

Repayments Exceeding Outstanding Principal Revert Instead of Refunding Excess

Informational

1.7AO:A/AC:L/AX:M/R:N/S:U/C:N/A:L/I:N/D:N/Y:NAO:A/AC:L/AX:M/R:N/S:U/C:N/A:L/I:N/D:N/Y:N

Description

Recommendation

Remediation Comment

HAL-02Future Release

Native Tokens Sent Outside the Intended Flows Have No Recovery Operation

Informational

1.0AO:A/AC:L/AX:H/R:N/S:U/C:N/A:L/I:N/D:L/Y:NAO:A/AC:L/AX:H/R:N/S:U/C:N/A:L/I:N/D:L/Y:N

Description

Recommendation

Remediation Comment

HAL-03Future Release

Configuration Validation Does Not Check Destination Suitability or Vault Bindings

Informational

1.0AO:A/AC:L/AX:H/R:N/S:U/C:N/A:L/I:L/D:N/Y:NAO:A/AC:L/AX:H/R:N/S:U/C:N/A:L/I:L/D:N/Y:N

Description

Recommendation

Remediation Comment

HAL-04Future Release

New Draws Are Not Gated on the Receipt Reconciliation Invariant

Informational

0.0AO:A/AC:L/AX:L/R:N/S:U/C:N/A:N/I:N/D:N/Y:NAO:A/AC:L/AX:L/R:N/S:U/C:N/A:N/I:N/D:N/Y:N

Description

Recommendation

Remediation Comment

Disclaimer#

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.