The flaw in browser‑use web‑ui causes the system to write configured LLM API keys to disk as plain‑text JSON files without encryption or access restrictions. This permits an attacker who can read the temporary settings directory to recover the keys. The weakness is a clear‑text storage of sensitive information (CWE-312), which could lead to a confidentiality breach of credentials that unlock external LLM services for unauthorized use. The impact is mainly the exposure of those credentials, potentially enabling abuse or cost escalation.

The vulnerability affects browser‑use web‑ui versions 2.0.0 through 3.0.0. It has been identified in the webui_manager.py component and causes keys to be stored in a predictable temp settings location. No other vendors or product lines are listed as affected.

The CVSS score of 6.8 indicates a moderate severity. The EPSS score is not available, so the current likelihood of exploitation is unclear. This issue is not listed in the CISA KEV catalog. Attack can occur via a local file‑read vector: an attacker with read access to the temporary settings directory can retrieve the keys. Because the vulnerability does not rely on network exposure, exploitation requires either local or privileged access, making the risk moderate but still significant for hosts with broad temporary directory permissions.