Open WebUI — Vulnerability (CVE-2026-44557)
Date: 2026-05
Affected: openwebui/open_webui
Attack vector: auth-bypass
Category: vulnerability-disclosure
Severity: Medium
CVE: CVE-2026-44557
CWE: CWE-863
CVSS: 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N)

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, the _validate_collection_access function uses an incomplete allowlist that only enforces ownership checks for collections matching user-memory-* and file-* patterns. All other collection names pass through unchecked — including the system-level knowledge-bases meta-collection, which stores the IDs, names, and descriptions of every knowledge base on the instance. Any authenticated user can query this meta-collection directly via the retrieval query endpoints to obtain a global index of all knowledge bases across all users. This vulnerability is fixed in 0.9.0.


Mitigations:

Architectural layers (MAESTRO):