IBM Langflow OSS versions 1.0.0 through 1.10.0 allow unauthenticated attackers to create unlimited user accounts. When the deployment flag NEW_USER_IS_ACTIVE is true, these accounts are immediately active, giving the attacker the ability to authenticate normally and reach RCE endpoints, bypassing the standard authentication flow. The vulnerability is categorized as CWE-306, which describes a lack of or improper authentication controls.

The affected product is IBM Langflow OSS, specifically versions 1.0.0 to 1.10.0. The library is distributed via the IBM package name langflow_oss and available on PyPI.

The CVSS score is 9.8, indicating critical severity. The EPSS score is less than 1%, suggesting a low but non‑zero exploitation probability. The vulnerability is not listed in the CISA KEV catalog, yet the high CVSS score and the ability to create active accounts without authentication make it a prime target for attackers who can simply contact the open registration endpoint. Exploitation requires only network access to the Langflow instance; no local privileges or prior authentication are needed. Once an active user is created, the attacker can authenticate and invoke RCE endpoints, achieving full system compromise.