Authorization bypass through user-controlled key in Open WebUI - CVE-2026-45671
Published: May 12, 2026
Vulnerability identifier: #VU131122
CSH Severity: Medium
CVSS v4: 8.5 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-45671
CWE-ID: CWE-639
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to read, modify, and delete arbitrary files owned by other users.
The vulnerability exists due to improper access control in has_access_to_file() in backend/open_webui/routers/files.py when handling file access requests for files referenced by shared chats. A remote user can send crafted requests to file endpoints using a valid file UUID to read, modify, and delete arbitrary files owned by other users.
User interaction is required because the target file must be referenced in a shared chat, and file UUIDs may be disclosed to users with read access to a knowledge base via GET /api/v1/knowledge/{id}/files.
Affected software
Open WebUI
How to mitigate CVE-2026-45671
Install security update from vendor's website.
Open WebUI - update to 0.9.0