Home › CVE Intelligence › CVE-2026-54011
CVSS 8.7 HIGH Vulnerability

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

Summary 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-con…

8.7CVSS Score
HIGHSeverity
NOCISA KEV
VulnerabilityImpact Type

📋 Vulnerability Details

CVE IDCVE-2026-54011
Vendorpip
Affected Productopen-webui
Vulnerability TypeVulnerability
CVSS Score8.7 (HIGH)
Actively Exploited❌ No known exploitation
Patch StatusSee Vendor Advisory →
Reported ByCYBERDUDEBIVASH SENTINEL APEX Intelligence (via github_advisories)

🔬 Technical Analysis

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Summary 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 is a confirmed stored XSS vulnerability reachable through normal product functionality.

Affected Version - main

• Reproduced on v0.8.12

Affected Code Mermaid is initialized in permissive mode: https://github.com/open-webui/open-webui/blob/9bd84258d09eefe7bf975878fb0e31a5dadfe0f8/src/lib/utils/index.ts#L1698

The file preview path renders Me

🎯 Known Indicators of Compromise

{"type":"sha1","value":"9bd84258d09eefe7bf975878fb0e31a5dadfe0f8","confidence_score":0.9,"first_seen":"2026-06-17","source_count":1} {"type":"url","value":"https://github.com/open-webui/open-webui/blob/9bd84258d09eefe7bf975878fb0e31a5dadfe0f8/src/lib/utils","confidence_score":0.82,"first_seen":"2026-06-17","source_count":1}

📚 Advisory References

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