CVE-2026-45339 Open WebUI's API key endpoint restrictions bypassed via `x-api-key` header — full message processing on restricted endpoints
Attackers can bypass API key restrictions on restricted endpoints by using the x-api-key header instead of Authorization, allowing unauthorized model invocation.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-45339?
CVE-2026-45339 is a medium-severity authentication bypass vulnerability in Openwebui Open Webui, published on 15 May 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.0, Open WebUI allows admins to restrict which API endpoints an API key can access. When an API key is restricted from /api/v1/messages, requests using the Authorization: Bearer sk-... header are correctly blocked with 403. However, the same key sent via the x-api-key header bypasses the restriction entirely — the request is authenticated, the model is invoked, and a full response is returned. This vulnerability is fixed in 0.9.0.
Weakness: CWE-863
Which versions are affected by CVE-2026-45339?
3 open source packages ship an affected version, including open-webui and open-webu. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
open-webui PyPI | All versions | 0.9.0 |
open-webu PyPI | All versions | 0.9.0 |
open-webu PyPI | All versions | 0.9.0 |
Products include Openwebui Open Webui.
How do I fix CVE-2026-45339?
Upgrade open-webui to 0.9.0 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-45339 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45339 exists.
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-57q6-fvp4-pqmm, PYSEC-2026-3543.