CVE-2026-45399 Open WebUI: Low-privilege authenticated users can enumerate and stop global background tasks, causing system-wide chat disruption
Low-privilege users can enumerate and stop other users' background tasks, causing system-wide chat disruption in Open WebUI.
- 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-2026-45399?
CVE-2026-45399 is a high-severity missing authorization vulnerability in Openwebui Open Webui, published on 15 May 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 0.9.0, any authenticated user with low privileges can enumerate active background tasks across the system and stop tasks belonging to other users via the GET /api/tasks and POST /api/tasks/stop/{task_id} methods. This allows a casual user to disrupt system-wide chat usage by continuously canceling other users' active tasks. This is a real authorization vulnerability affecting integrity and usability in multi-user deployments. This vulnerability is fixed in 0.9.0.
Weakness: CWE-862
Which versions are affected by CVE-2026-45399?
3 open source packages ship an affected version, including open-webui. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
open-webui PyPI | All versions | 0.9.0 |
open-webui PyPI | All versions | 0.9.0 |
open-webui PyPI | All versions | 0.9.0 |
Products include Openwebui Open Webui.
How do I fix CVE-2026-45399?
Upgrade open-webui to 0.9.0 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-45399 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-45399 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-8jjp-r2w2-4v22, PYSEC-2026-2714.