Improper access control in Open WebUI - CVE-2026-54021
Published: June 30, 2026
Vulnerability identifier: #VU135949
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-54021
CWE-ID: CWE-284
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Open WebUI
Affected software:
Open WebUI
Open WebUI
Detailed vulnerability description
The vulnerability allows a remote user to access restricted Ollama backend resources.
The vulnerability exists due to improper access control in indexed Ollama proxy routes in backend/open_webui/routers/ollama.py when handling caller-supplied url_idx path parameters. A remote user can supply a crafted url_idx value to access restricted Ollama backend resources.
Requests are forwarded using the target backend's configured API key, and admin-disabled backends remain reachable through indexed routes because the disabled state is not re-checked at request time.
How to mitigate CVE-2026-54021
Install security update from vendor's website.