Open WebUI's API endpoint /api/v1/retrieval/query/collection can be used by any authenticated user to read the private memories of other users. This vulnerability is an insecure direct object reference (IDOR), allowing an attacker to access confidential data that should be isolated to the owner. The weakness is identified as CWE-639, an access control issue that permits read operations across user boundaries, potentially exposing sensitive personal information.

The affected product is Open WebUI. All releases prior to version 0.8.6 are impacted. Users running those versions should upgrade to 0.8.6 or later to receive the fix.

The CVSS score is 3.1, indicating low severity, and the EPSS score is below 1%, suggesting a low likelihood of exploitation in the wild. The vulnerability is not listed in CISA's KEV catalog. Attackers must first authenticate to the system, after which they can directly call the vulnerable API endpoint to retrieve another user's data. Because the flaw only grants read access and there are no known privilege escalation steps, the impact is limited to confidentiality leakage, not a broader system compromise.