CVE-2026-40322

CRITICAL 9.1

SiYuan: Mermaid `javascript:` Link Injection Leads to Stored XSS and Electron RCE

CVSS Score

9.1

EPSS Score

0.0%

EPSS Percentile

0th

SiYuan is an open-source personal knowledge management system. In versions 3.6.3 and below, Mermaid diagrams are rendered with securityLevel set to "loose", and the resulting SVG is injected into the DOM via innerHTML. This allows attacker-controlled javascript: URLs in Mermaid code blocks to survive into the rendered output. On desktop builds using Electron, windows are created with nodeIntegration enabled and contextIsolation disabled, escalating the stored XSS to arbitrary code execution when a victim opens a note containing a malicious Mermaid block and clicks the rendered diagram node. This issue has been fixed in version 3.6.4.

CWE	CWE-79 CWE-94
Vendor	siyuan-note
Product	siyuan
Published	Apr 16, 2026

Stay Ahead of the Next One

Get instant alerts for siyuan-note siyuan

Be the first to know when new critical vulnerabilities affecting siyuan-note siyuan are published — delivered to Slack, Telegram or Discord.

Get Free Alerts → Free · No credit card · 60 sec setup

CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

siyuan-note / siyuan

< 3.6.4

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/siyuan-note/siyuan/security/advisories/GHSA-x63q-3rcj-hhp5 github.com: https://github.com/siyuan-note/siyuan/releases/tag/v3.6.4