CVE-2026-42862: Flowise: mass assignment breaks tenant isolation

### Summary A Mass Assignment vulnerability exists in the tool update endpoint of FlowiseAI. The endpoint allows authenticated users to modify server-controlled properties such as workspaceId, createdDate, and updatedDate when updating a tool resource. Due to missing server-side validation and authorization checks, an attacker can manipulate the workspaceId field and reassign tools to arbitrary workspaces. This breaks tenant isolation in multi-workspace environments. ### Details The endpoint responsible for updating tools: **PUT /api/v1/tools/{toolId}** accepts a JSON request body containing tool metadata. However, the server does not restrict which properties may be modified by the client. As a result, user-controlled request bodies can include additional fields that should normally be controlled only by the backend. Server-controlled fields that can be manipulated include: 1. workspaceId 2. createdDate 3. updatedDate The request body is directly merged into the underlying database entity without proper DTO validation or authorization checks. ### PoC Authenticate to the Flowise interface. Capture the request used to update a tool: ```http PUT /api/v1/tools/<TOOL_ID> Content-Type: application/json Modify the request body by injecting additional fields: { "name": "aaa", "description": "bbb", "color": "linear-gradient(rgb(109,215,45), rgb(136,170,134))", "schema": "[]", "func": "", "iconSrc": "test", "workspaceId": "11111111-2222-3333-4444-555555555555", "createdDate": "1995-03-06T14:17:50.000Z", "updatedDate": "1995-03-06T14:17:50.000Z" } ``` Send the request. Observe that the response includes the manipulated fields: ```json { "workspaceId": "11111111-2222-3333-4444-555555555555", "createdDate": "1995-03-06T14:17:50.000Z" } ``` This confirms that client-controlled values are accepted and persisted by the server. ### Impact This vulnerability allows authenticated users to manipulate internal attributes of tool resources. Confirmed impacts include: - Cross-workspace reassignment of tools (workspaceId) - Unauthorized modification of metadata (createdDate, updatedDate) In multi-tenant deployments, this may allow an attacker to move tools between workspaces without authorization, breaking tenant isolation boundaries.

An attacker obtains valid credentials to a low-privilege workspace in a shared Flowise deployment — through credential theft, account takeover, or legitimate signup on a multi-tenant instance. Using the standard Flowise UI, they capture a tool update request via browser developer tools or a proxy. They modify the JSON body to inject a target workspaceId (obtained through enumeration, leaked configuration, or insider knowledge) and send the manipulated PUT request. The server accepts and persists the attacker-controlled workspaceId without validation, moving the tool into the target workspace. The attacker also sets createdDate and updatedDate to historical values to obscure the modification in audit logs. If the reassigned tool contained embedded API keys or privileged system access in its schema/func fields, those credentials are now accessible to anyone in the target workspace. The attacker repeats across multiple tools and workspaces, systematically dismantling tenant isolation while appearing as a normal authenticated user in access logs.