Open WebUI from 0.6.0 before 0.11.4 contains an improper access control vulnerability in has_access_to_file that lets former knowledge base… (CVE-2026-109285)

The vulnerability in Open WebUI affects versions starting from 0.6.0 before 0.11.4. It arises from improper access control in the has_access_to_file function, which fails to revoke file access for former knowledge base collaborators due to stale cached references. As a result, attackers who have read or write grants can exploit the file content endpoint to download or delete files, including those removed or belonging to private knowledge bases.

Attackers with existing read or write permissions can exploit this vulnerability to access or delete files they should no longer have access to, including files from private knowledge bases. This could lead to unauthorized data disclosure and data loss. The CVSS score of 5.0 (medium severity) reflects limited impact due to required privileges and high attack complexity.

No official patch or fix information is provided in the available data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict read and write permissions carefully and monitor for unauthorized file access or deletion attempts.