XSS in Open-Webui
CVE-2026-54011
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.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.003 (27.0th 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 < 0.9.6
- Openwebui Open_webui
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-54011?
- CVE-2026-54011 is a high-severity vulnerability in Open-Webui, classified under Cross-site Scripting. CVSS score: 8.7/10. Published 2026-06-23.
- How severe is CVE-2026-54011?
- High severity. CVSS v3 base score is 8.7 out of 10.