CVE-2026-70492 Open WebUI: Stored XSS via unescaped KaTeX render-error fallback in rendered messages
Attackers can inject malicious scripts via KaTeX error fallbacks in chat messages, stealing session tokens or taking over admin accounts.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-70492?
CVE-2026-70492 is a high-severity cross-site scripting vulnerability in Openwebui Open Webui, published on 4 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.10.0 until 0.11.0, src/lib/components/chat/Messages/Markdown/KatexRenderer.svelte could store and render a chat message whose math block makes KaTeX fail with a stack overflow instead of a parse error. The catch branch fell back to inserting the original math source into the page as HTML through {@html} rather than as text, so script in the message runs in the browser of whoever views it, including shared chats and channels. The viewer's session token in localStorage can be stolen, and an administrator viewer can have their account taken over. This issue is fixed in 0.11.0.
Weakness: CWE-79
Which versions are affected by CVE-2026-70492?
3 open source packages ship an affected version, including open-webui. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
open-webui PyPI | From 0.10.0 | 0.11.0 |
open-webui PyPI | From 0.10.0 | 0.11.0 |
open-webui PyPI | From 0.10.0 | 0.11.0 |
Products include Openwebui Open Webui.
How do I fix CVE-2026-70492?
Upgrade open-webui to 0.11.0 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-70492 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-70492 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-pwxh-7358-jq2x, PYSEC-2026-3650.