Vulnerability · Published Jun 23, 2026 · Assigned by GitHub_M

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

High 8.7

In plain English

A high-severity cross-site scripting in open-webui from open-webui. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.7High

Exploit odds (30 days)0.3%top 72.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	open-webui	0.9.6	GHSA-v8qj-hxv7-mgvv
PyPI	open-webui	0.9.6	PYSEC-2026-2759

Affected products (as reported)

Vendor	Product	Versions
open-webui	open-webui	< 0.9.6

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

References

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