CVE-2026-54011

High

Description

Open WebUI is a self-hosted artificial intelligence platform designed to operate entirely offline. Prior to 0.9.6,Open WebUI renders Mermaid blocks from Markdown files in the file preview panel and inserts the generated SVG into the DOM using innerHTML. Because Mermaid is configured with securityLevel: 'loose', attacker-controlled Mermaid content can be rendered unsafely in this flow. A working payload was validated through the Markdown preview path, resulting in JavaScript execution in the victim’s browser under the application origin. This vulnerability is fixed in 0.9.6.

SeverityHigh

CVSS8.7

Exploit probability—

ProductOpenwebui Open Webui

PublishedJun 23, 2026

First seenJun 23, 2026

Weakness typeCWE-79Cross-site scripting (XSS)

How to fix

Update

openwebui open_webui0.9.6 or later
open-webui0.9.6 or later

Affected products

Product	Affected versions	Fixed in
openwebui open_webui	v < 0.9.6	0.9.6
open-webuiPyPI	v < 0.9.6	0.9.6

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