Flowise Mass Assignment Vulnerability in Evaluator Management Allows Cross-Workspace Takeover

A mass assignment vulnerability has been identified in Flowise, a user interface for building customized large language model flows. This issue, present in versions through 3.1.1, allows for cross-workspace evaluator takeover by improperly handling workspace-related data during evaluator creation and updates. The vulnerability arises because the Evaluator controller does not validate which fields can be overwritten with client-controlled data, enabling authenticated users to manipulate evaluator ownership and access across workspaces.

Impact

Exploitation of this vulnerability allows authenticated users to take over evaluators from other workspaces, disrupting workspace boundaries and access controls. This could lead to unauthorized visibility and modification of evaluators and their associated scoring rubrics.

Reproduction

To reproduce this vulnerability, an authenticated user must first create or identify an evaluator in their workspace. They can then send a request to update the evaluator, including a workspace ID from a different workspace. The request will be processed as if it originated from the user's current workspace, but will transfer the evaluator to the other workspace, effectively taking it over.

Remediation

Users can update to Flowise version 3.1.2, where this vulnerability has been patched.