What’s Vulnerable › Vulnerabilities

CVE-2026-54011: Open WebUI: Stored XSS in Mermaid Markdown Preview

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-06-23 · updated 2026-06-25
• Weakness: CWE-79

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.

Affected products

• open-webui: before 0.9.6 — fixed in 0.9.6

How to fix

Upgrade to a fixed version: open-webui 0.9.6. Check the vendor advisory for mitigations.

References

• https://github.com/open-webui/open-webui/security/advisories/GHSA-v8qj-hxv7-mgvv
• https://github.com/open-webui/open-webui/security/advisories/GHSA-v8qj-hxv7-mgvv

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