Open WebUI: Stored XSS via unescaped KaTeX render-error fallback in rendered messages
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-79.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| open-webui | open-webui | 0.10.0 to before 0.11.0 | 0.11.0 | Patch available | CNA |
| — | open-webui (PyPI) | 0.10.0 to before 0.11.0 | 0.11.0 | Patch available | GHSA-pwxh-7358-jq2x |
- open-webui Vendoropen-webui Affected 0.10.0 to before 0.11.0 Fixed in 0.11.0 Patch available CNA
- open-webui (PyPI) Vendor— Affected 0.10.0 to before 0.11.0 Fixed in 0.11.0 Patch available GHSA-pwxh-7358-jq2x
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:* | 0.10.0 to before 0.11.0 | Vulnerable | open-webui |
- cpe:2.3:a:openwebui:open_webui:*:*:*:*:*:*:*:* Versions 0.10.0 to before 0.11.0 Vulnerable ·open-webui
Remediation
- Fix · CNA open-webui (open-webui) Fixed in 0.11.0
- Fix · GHSA-pwxh-7358-jq2x open-webui (PyPI) Fixed in 0.11.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-70492
- 2026-10-03 Alias added: GHSA-pwxh-7358-jq2x
References
Patch 2
More open-webui Open Webui vulnerabilities
- TI-2024-06216 Open WebUI Arbitrary File Upload + Path Traversal CVSS 3.1HIGH 8.8
- TI-2024-07467 Improper Authentication in open-webui/open-webui CVSS 3.1HIGH 8.2
- TI-2026-42359 Open WebUI: Cross-user code-interpreter and tool execution via unvalidated Socket.IO event-caller session_id CVSS 3.1CRITICAL 9.0
- TI-2026-40759 open-webui - Remote Code Execution via CORS Misconfiguration and Session Validation CVSS 4.0CRITICAL 9.0
- TI-2024-07431 Cross-site Scripting (XSS) in open-webui/open-webui CVSS 3.0CRITICAL 9.0
- TI-2026-60021 Open WebUI: Same-origin XSS to account takeover via terminal port-preview iframe hardcoding allow-same-origin CVSS 3.1HIGH 8.7
Sources
- CVE-2026-70492 · CVE Program
- CVE-2026-70492 · NVD
- FIRST EPSS
- GHSA-pwxh-7358-jq2x · GitHub Advisory Database · CC BY 4.0
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