CVE-2026-40322

Received

Published: 16 Apr 2026, 23:00

Last modified:16 Apr 2026, 23:00

Vulnerability Summary

Overall Risk (default)

high

70/100

CVSS Score

9.1 CRITICAL

v3.1 (cve.org)

EPSS Score

No data

KEV

Not listed

Ransomware

No reports

Public exploits

None found

Dark Web

Not detected

Timeline

16 Apr 2026, 23:00

Published

Vulnerability first disclosed

Description

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.

CVSS Metrics

v3.1•CRITICAL•Score: 9.1CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Techniques & Countermeasures

CWE-79•Improper 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.
CWE-94•Improper Control of Generation of Code ('Code Injection')
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

Affected Systems

siyuan-note•siyuan
< 3.6.4