CVE-2026-54011
Open WebUI: Stored XSS in Mermaid Markdown Preview
CVSS Score
8.7
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-79 |
| Vendor | open-webui |
| Product | open-webui |
| Published | Jun 23, 2026 |
| Last Updated | Jun 23, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None
Affected Versions
open-webui / open-webui
< 0.9.6