CVE-2026-87013

Open WebUI, a widely used self-hosted AI platform, contains a loop with an unreachable exit condition (CWE-835) in its folder-hierarchy handling. From version 0.10.0 until 0.11.1, the endpoint POST /api/v1/folders/{id}/update/parent allowed an authenticated user to set a folder's parent to itself or one of its descendants, creating a cycle in the folder tree. Because the tree walks used by DELETE /api/v1/folders/{id} and POST /api/v1/folders/{id}/read did not track visited folder IDs, triggering those endpoints on a cyclic tree consumed CPU and memory indefinitely, degrading or crashing the instance until the stored data was repaired. An attacker gains only a denial-of-service capability (no confidentiality or integrity impact), and exploitation requires a valid account, limiting the attack surface to multi-tenant deployments with untrusted users. The issue is fixed in version 0.11.1; no exploitation in the wild is known, though a public security advisory describing the flaw exists.

What to do: Upgrade Open WebUI to version 0.11.1 or later (via pip or the official Docker image) to receive the fix. Administrators of shared or multi-user instances should audit folder trees for parent cycles (a folder appearing among its own ancestors) and remove them, since a persisted cycle keeps consuming resources until repaired. Restrict account creation and review logs for repeated calls to /api/v1/folders/{id}/update/parent followed by delete/read operations as an indicator of abuse.