Mermaid does not properly sanitize architecture diagram iconText leading to XSS
Published Aug 19, 2025 · Updated Nov 3, 2026
Original summary
Normalized public record · Updated Nov 3, 2026
Mermaid does not properly sanitize architecture diagram iconText leading to XSS
Publisher and source text is retained separately from QFinch interpretation.
QFinch assessment
In the default configuration of mermaid 11.9.0, user supplied input for architecture diagram icons is passed to the d3 html() method, creating a sink for cross site scripting.
Potential impact
XSS on all sites that use mermaid and render user supplied diagrams without further sanitization.
Technical context
Architecture diagram service iconText values are passed to the d3 html() method, allowing malicious users to inject arbitrary HTML and cause XSS when mermaid-js is used in it's default configuration. The vulnerability lies here: This issue was introduced with 734bde38777c9190a5a72e96421c83424442d4e4, around 15 months ago, which was released in v11.1.0.
Evidence: public source recordsAffected products
| Affected package, product or range | Fix status |
|---|---|
| Consult the referenced vendor advisory for affected versions. | Consult source advisory |
Matching a version is only one part of assessing exposure. QFinch has not assessed your environment on this public page.
Remediation
Apply the vendor-supported fixed release or mitigation, then verify the affected component is no longer reachable.
- Confirm the affected product and reachable code path exist in your environment.
- Apply the vendor-supported patch or mitigation from the primary advisory.
- Rescan the exact deployed revision and retain verification evidence.
Evidence coverage
- SSVC priority
- LOW
- Confidence
- Not available
- Aliases
- None reported
Scores appear only when corresponding evidence exists. Missing data is never interpreted as zero risk.
Sources and record history
Record history
Published Aug 19, 2025 · Last refreshed Nov 3, 2026