CVE-2026-70492 PUBLISHED

Open WebUI: Stored XSS via unescaped KaTeX render-error fallback in rendered messages

Assigner: GitHub_M
Reserved: 04.08.2026 Published: 04.08.2026 Updated: 05.08.2026

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.

Metrics

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
CVSS Score: 8.7

Product Status

Vendor open-webui
Product open-webui
Versions
  • Version >= 0.10.0, < 0.11.0 is affected

References

Problem Types

  • CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') CWE