The vulnerability resides in an improper access control check within the has_access_to_file functionality. It allows users who previously had collaborator rights in a knowledge to retain access to files that have been removed, using stale cached references. An attacker with either read or write permissions can download these removed files through the file content endpoint or delete them, even from private knowledge bases owned by others. This results in unauthorized data disclosure and potential data loss.

The flaw affects Open WebUI version 0.6.0 through versions before 0.11.4. The affected vendor is open‑webui and the product is Open WebUI.

The CVSS score is 2.3, indicating low severity, and the EPSS score is not available. The vulnerability is not listed in the CISA KEV catalog. Attackers need only possess existing read or write privileges in a knowledge base; no additional permissions are required. The likely attack vector is through the web interface, where a user can access the file content endpoint to retrieve or delete stale files.