CVE-2026-109299 Open WebUI 0.9.0 before 0.11.4 Denial of Service via Recurrence Rule Validation
Authenticated users with automation permissions can cause denial of service by submitting invalid recurrence rules that block the event loop.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-109299?
CVE-2026-109299 is a high-severity denial of service vulnerability in open-webui, published on 12 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Open WebUI from 0.9.0 before 0.11.4 contains a denial of service vulnerability that allows authenticated users with automations permission to stall the instance by submitting unsatisfiable recurrence rules. Attackers can repeatedly send rules like February 30th to the automations create or update endpoints, blocking the shared event loop for seconds per request.
Which versions are affected by CVE-2026-109299?
How do I fix CVE-2026-109299?
No fix has been published for CVE-2026-109299 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-109299 being exploited?
There is no known exploitation of CVE-2026-109299 in the wild and no public exploit code.
Sources
Also known as GHSA-5w58-mwmh-vf2m, GHSA-vp3m-gw6c-whgh.