XSS in Open-Webui
CVE-2026-70492
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.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.003 (18.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.7 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N.
Affected products
- Open-webui — versions >= 0.10.0, < 0.11.0
- Openwebui Open_webui
Weakness classification (CWE)
References
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (Patch, x_refsource_MISC, Vendor Advisory)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-70492?
- CVE-2026-70492 is a high-severity vulnerability in Open-Webui, classified under Cross-site Scripting. CVSS score: 8.7/10. Published 2026-08-04.
- How severe is CVE-2026-70492?
- High severity. CVSS v3 base score is 8.7 out of 10.