CVE-2026-109300
Medium
Description
Open WebUI from 0.6.31 before 0.11.4 contains a stored cross-site scripting vulnerability in its Markdown renderer, which treats user-authored tool-call details blocks as tool output and mounts their embeds attribute in script-enabled iframes. Authenticated users can post crafted channel messages, chat messages, or citation content that runs JavaScript in viewers' browsers, enabling in-app phishing, or session hijacking where iframeSandboxAllowSameOrigin is enabled.
SeverityMedium
CVSS4.6
Exploit probability—
ProductOpen-webui
PublishedOct 12, 2026
First seenOct 12, 2026
Weakness typeCWE-79Cross-site scripting (XSS)
How to fix
Update
- open-webui open-webui0.11.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| open-webui open-webui | 0.6.31 ≤ v < 0.11.4 | 0.11.4 |
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