Open WebUI — Vulnerability (CVE-2026-44552)
Date: 2026-05
Affected: openwebui/open_webui
Attack vector: other
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2026-44552
CWE: CWE-668
CVSS: 8.7 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N)

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, the tool_servers and terminal_servers keys in utils/tools.py do use a prefix. When two or more Open WebUI instances share a Redis database (a supported and documented deployment pattern, e.g., for multi-region deployments, blue-green setups, or cluster topologies), the unprefixed keys collide. An admin on Instance A writing to tool_servers overwrites the value read by Instance B — causing Instance B's users to receive Instance A's tool server configuration. This vulnerability is fixed in 0.9.0.


Mitigations:

Architectural layers (MAESTRO):