GHSA-2364-jh4q-m9vm: Flowise: IDOR exposes customer PII and billing data

### Summary An Insecure Direct Object Reference (IDOR) vulnerability exists at the **GET /api/v1/organization/customer-default-source** endpoint. This flaw allows an authenticated attacker to bypass authorization checks and retrieve sensitive payment and profile information of other customers by manipulating the customerId parameter. The exposed data includes email addresses, account balances, currency types, and internal billing configurations. ### Details The application fails to implement proper object-level access control. While the endpoint requires a valid session/token, it does not verify if the requesting user has the authority to access the specific customerId provided in the query string. When a request is made to: GET /api/v1/organization/customer-default-source?customerId=cus_XXXX The server processes the request based solely on the existence of a valid session, returning the data associated with the ID regardless of the data owner's identity. Since customer IDs follow a predictable pattern (Stripe-formatted cus_...), an attacker could potentially enumerate these IDs to scrape customer data. ### PoC 1. To reproduce the vulnerability, follow these steps: 2. Log in to your account at cloud.flowiseai.com. 3. Capture a request to the payment source endpoint using a proxy tool (e.g., Burp Suite). 4. Change the customerId parameter in the URL to a target user's ID (e.g., cus_U9ajkQvu0e67uH). Execute the request: ``` GET /api/v1/organization/customer-default-source?customerId=cus_U9ajkQvu0e67uH HTTP/2 Host: cloud.flowiseai.com Cookie: [YOUR_AUTHENTICATED_COOKIES] ... ``` Response: ``` { "id": "cus_U9ajkQvu0e67uH", "object": "customer", "email": "truongnguyen210044@gmail.com", "balance": 0, "currency": "usd", "invoice_settings": { "custom_fields": null, "default_payment_method": null }, "livemode": true ... } ``` The server returns a 200 OK status with the private data of the target customer. ### Impact - Vulnerability Type: Broken Access Control (IDOR). - Impacted Parties: All registered users and organizations on the FlowiseAI Cloud platform. - Consequences: * Data Privacy Breach: Exposure of Personally Identifiable Information (PII) such as email addresses. - Financial Information Leakage: Disclosure of account balances, currency settings, and invoice metadata. - Compliance Risk: Potential violation of data protection regulations (e.g., GDPR) due to unauthorized access to user billing profiles.

An attacker signs up for a legitimate Flowise Cloud account (low barrier, self-service signup) and uses a proxy tool like Burp Suite to capture a normal request to the customer-default-source endpoint. Recognizing the customerId follows Stripe's predictable cus_XXXX format, the attacker methodically substitutes different values — either guessed, leaked from other sources, or harvested from public references — and replays the authenticated request. Each successful substitution returns another tenant's email, account balance, currency, and invoice settings with a 200 OK, allowing the attacker to build a scraped database of Flowise customer PII and billing profiles for resale, targeted phishing, or account-takeover reconnaissance against high-value tenants.