IBM Langflow OSS versions 1.0.0 through 1.10.0 contain an authentication flaw in the /api/v1/login/auto_login endpoint. When the AUTO_LOGIN configuration is enabled – which is the default – the endpoint issues long‑lived superuser bearer tokens without requiring any user credentials. The flaw is categorized as CWE‑306 (Missing Authentication) and allows an attacker to obtain full administrative privileges simply by sending a request to the endpoint. In addition, permissive cross‑origin resource sharing (CORS) settings can expose the issued tokens to unintended origins, increasing the risk of unintended token disclosure.

The vulnerability affects IBM Langflow OSS releases from 1.0.0 up to and including 1.10.0. The default configuration includes the AUTO_LOGIN feature enabled, allowing the flaw to be exploited in a typical deployment.

The CVSS score of 9.8 indicates critical impact. The EPSS score is below 1%, suggesting a low current exploitation probability, and the vulnerability is not listed in the CISA KEV catalog. An attacker can exploit this flaw remotely over the network without any authentication. Per the description, the attack vector is a direct network request to the exposed endpoint, optionally amplified by permissive CORS settings that could reveal tokens to external origins.