🛡️ CVE-2026-40107
🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-918 NVD
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

SiYuan is a personal knowledge management system. Prior to 3.6.4, SiYuan configures Mermaid.js with securityLevel: "loose" and htmlLabels: true. In this mode, tags with src attributes survive Mermaid's internal DOMPurify and land in SVG blocks. The SVG is injected via innerHTML with no secondary sanitization. When a victim opens a note containing a malicious Mermaid diagram, the Electron client fetches the URL. On Windows, a protocol-relative URL (//attacker.com/image.png) resolves as a UNC path (\\attacker.com\image.png). Windows attempts SMB authentication automatically, sending the victim's NTLMv2 hash to the attacker. This vulnerability is fixed in 3.6.4.

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CWE CWE-918
Public Exploit ✅ No
Source NVD
Published 2026-04-10
Updated 2026-06-02
Modified 2026-04-10
Fix URL N/A

Affected Packages

Software From version Fixed in
github.com/siyuan-note/siyuan/kernel — —
siyuan — 3.6.4

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