CVE-2026-54011: open-webui Cross-site Scripting

Vulnerability summary

CVE-2026-54011 is a high (CVSS 8.7) Cross-site Scripting vulnerability in open-webui. EPSS estimates a 0.34% chance of exploitation in the next 30 days, higher than 25.6% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 23-06-2026
   PublishedVulnerability first disclosed.
2. 23-06-2026
   Last modifiedVulnerability information updated.

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.

• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.