CVE-2026-70493 Open WebUI: Any authenticated user can stall a worker via a knowledge-search pattern that backtracks catastrophically
Authenticated users can cause denial of service in Open WebUI by submitting catastrophic backtracking regex patterns in knowledge searches.
- 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-2026-70493?
CVE-2026-70493 is a medium-severity denial of service vulnerability in Openwebui Open Webui, published on 4 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.6 until 0.11.0, the built-in knowledge search path in backend/open_webui/tools/knowledge_fs.py and backend/open_webui/tools/builtin.py let a chat participant choose a pattern used to grep knowledge files. Patterns containing regex metacharacters were compiled with Python's backtracking re engine and run against every line of every reachable file with no time limit, so a crafted pattern such as (x|x)*y and one matching uploaded file line can pin one CPU core and block the event loop. This causes availability impact for every other user of the affected worker. This issue is fixed in 0.11.0.
Weakness: CWE-1333
Which versions are affected by CVE-2026-70493?
3 open source packages ship an affected version, including open-webui. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
open-webui PyPI | From 0.9.6 | 0.11.0 |
open-webui PyPI | From 0.9.6 | 0.11.0 |
open-webui PyPI | From 0.9.6 | 0.11.0 |
Products include Openwebui Open Webui.
How do I fix CVE-2026-70493?
Upgrade open-webui to 0.11.0 or later.
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-2026-70493 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-70493 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-2f54-p244-32q6, PYSEC-2026-3637.