Executive Summary

CVE-2025-15085 is an improper authorization vulnerability in the youlai-mall software affecting the balance deduction functionality. Specifically, the deductBalance function in MemberController.java allows any authenticated user to deduct balance amounts from any other user's account without verifying ownership or permissions. This means an attacker with a valid login token can specify another user's memberId and reduce their balance arbitrarily. The vulnerability arises because there are no checks to ensure the memberId matches the authenticated user, no role-based access control, and no auditing or rate limiting. This leads to horizontal privilege escalation (BOLA/IDOR), enabling unauthorized financial manipulation remotely. [1, 2]

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Impact Analysis

This vulnerability can lead to unauthorized financial loss as attackers can deduct funds from other users' accounts without permission. It enables horizontal privilege escalation, allowing attackers to manipulate balances across multiple accounts if they can enumerate memberIds. The lack of auditing and logging means attacks can go undetected, eroding user trust and damaging the platform's reputation. Additionally, it poses business risks such as financial loss, potential regulatory non-compliance, and increased exposure to automated large-scale attacks. [1, 3]

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Compliance Impact

The vulnerability leads to unauthorized access and manipulation of user financial data, which can violate security best practices required by standards like GDPR and HIPAA. The lack of proper authorization controls and auditing may result in non-compliance with data protection and financial transaction regulations, increasing legal and regulatory risks for the affected organization. [1, 2]

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Detection Guidance

This vulnerability can be detected by monitoring for unauthorized PUT requests to the endpoint `/mall-ums/app-api/v1/members/{memberId}/balances/_deduct` where the `memberId` does not match the authenticated user. A practical detection method is to look for suspicious or unexpected balance deduction requests using tools like curl or network monitoring. For example, you can test the endpoint with a command similar to: `curl -X PUT -H "Authorization: Bearer <token>" "https://<gateway>/mall-ums/app-api/v1/members/200/balances/_deduct?balance=10000"` and observe if the request succeeds without proper authorization checks. Additionally, monitoring logs for such PUT requests and verifying if authorization checks are enforced can help detect exploitation attempts. Since the vulnerability lacks auditing and logging, implementing custom logging or network traffic analysis focusing on this endpoint is recommended. [1]

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Mitigation Strategies

Immediate mitigation steps include restricting access to the vulnerable endpoint `/mall-ums/app-api/v1/members/{memberId}/balances/_deduct` to only trusted and authorized users, implementing strict authorization checks to ensure the `memberId` matches the authenticated user, and adding role-based access control to prevent unauthorized balance deductions. Since the vendor has not provided a patch or response, consider disabling or restricting this API endpoint temporarily. Monitoring and logging all requests to this endpoint to detect abuse is also critical. If possible, replace or upgrade the affected component with a secure alternative. Applying network-level controls such as firewall rules or API gateways to limit access can also reduce risk. [1, 2]

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