CVE-2026-54021 Open WebUI: Authenticated users can target arbitrary configured Ollama backends via unguarded url_idx path parameter
Authenticated users can bypass backend restrictions to access unauthorized Ollama servers by manipulating the url_idx parameter.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54021?
CVE-2026-54021 is a medium-severity missing authorization vulnerability in Openwebui Open Webui, published on 23 Jun 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.6, several direct, index-addressed Ollama proxy routes accept a caller-supplied url_idx path parameter and use it as a raw index into the admin-configured OLLAMA_BASE_URLS list. Access control on these routes validates only whether the user may use the requested model, never which backend the request is routed to. Any authenticated user can append an arbitrary url_idx to force their request onto an Ollama backend they were never authorized to reach, including internal, higher-privilege, or explicitly admin-disabled backends. This vulnerability is fixed in 0.9.6.
Weakness: CWE-863
Which versions are affected by CVE-2026-54021?
3 open source packages ship an affected version, including open-webui. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
open-webui PyPI | All versions | 0.9.6 |
open-webui PyPI | All versions | 0.9.6 |
open-webui PyPI | All versions | 0.9.6 |
Products include Openwebui Open Webui.
How do I fix CVE-2026-54021?
Upgrade open-webui to 0.9.6 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-54021 being exploited?
There is no known exploitation of CVE-2026-54021 in the wild and no public exploit code.
Other vulnerabilities in Openwebui Open Webui
- CVE-2026-44551 Open WebUI: LDAP Empty Password Authentication Bypass
- CVE-2026-56400 open-webui - Remote Code Execution via CORS Misconfiguration and Session Validation
- CVE-2024-8017 Cross-site Scripting (XSS) in open-webui/open-webui
- CVE-2026-45672 Open WebUI: Jupyter code execution works despite `ENABLE_CODE_EXECUTION=false` — feature gate bypassed
- CVE-2026-87995 Open WebUI: Same-origin XSS to account takeover via terminal port-preview iframe hardcoding allow-same-origin
Sources
Also known as GHSA-9rpj-v7hf-vv2w, PYSEC-2026-2718.