The vulnerability is a mass assignment issue in Flowise’s DocumentStore creation endpoint. By supplying a custom primary key and internal state fields, an authenticated user can cause the backend to perform an implicit UPSERT, thereby overwriting an existing DocumentStore object belonging to a different workspace. This breaks object‑level authorization and enables an attacker to tamper with or take over data that should be protected. The weakness is reflected in CWE‑284, CWE‑639, and CWE‑915.

Flowise, the open‑source drag‑and‑drop interface for building large language model pipelines, is affected for all versions earlier than 3.1.0. The issue manifests in deployments configured for multiple workspaces or tenants, where separate user groups share the same instance of the service. The affected component is the DocumentStore create endpoint exposed via HTTP POST, which accepts client‑supplied identifiers that are persisted without adequate validation.

The CVSS v3 score of 7.6 indicates a high severity, and while the EPSS score is below 1%, the vulnerability can be exploited by any authenticated user, making it potentially easier to compromise in production environments. Because the bug involves implicit UPSERT semantics, an attacker does not need administrative privileges but does require valid credentials to identify a target workspace’s DocumentStore ID. The attack is not listed in CISA KEV at this time, suggesting no publicly known exploitation yet, but the nature of the flaw warrants immediate attention.