Authenticated users can create a folder cycle by setting a folder as its own parent or as a descendant. The API that updates a folder’s parent does not detect such cycles, allowing the folder hierarchy to become recursive. When the system later walks this tree—for example, during a delete or read operation—the recursive path never terminates, causing an unbounded consumption of CPU time and memory. This resource exhaustion can degrade the service or render it unavailable to all users.

Open WebUI version 0.10.0 through 0.11.1 includes the affected API endpoints. The issue is resolved beginning with release 0.11.1, so systems running older versions of Open WebUI are vulnerable.

The attack vector requires authentication to the Open WebUI instance, as it relies on the POST /api/v1/folders/{id}/update/parent endpoint. An attacker can create a parent cycle and trigger the non-terminating request, leading to resource exhaustion. The CVSS score of 4.3 indicates a moderate impact, and the EPSS score is unavailable, so the likelihood of exploitation is unclear. The vulnerability is not listed in the CISA KEV catalog, suggesting no known active exploits.