CVE-2026-40107

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, <img> tags with src attributes survive Mermaid's internal DOMPurify and land in SVG <foreignObject> 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.

CVSS v3 6.5 MEDIUM

6.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/siyuan-note/siyuan/security/advisories/GHSA-w95v-4h65-j455	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:b3log:siyuan:*:*:*:*:*:*:*:*

History

16 Apr 2026, 20:28

Type	Values Removed	Values Added
CVSS	v2 : ~~unknown~~ v3 : ~~unknown~~	v2 : unknown v3 : 6.5
CPE		cpe:2.3:a:b3log:siyuan::::::::
First Time		B3log B3log siyuan
References	~~() https://github.com/siyuan-note/siyuan/security/advisories/GHSA-w95v-4h65-j455 -~~	() https://github.com/siyuan-note/siyuan/security/advisories/GHSA-w95v-4h65-j455 - Exploit, Vendor Advisory

09 Apr 2026, 21:16

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-04-09 21:16

Updated : 2026-04-16 20:28

NVD link : CVE-2026-40107

Mitre link : CVE-2026-40107

CVE.ORG link : CVE-2026-40107

JSON object : View

Products Affected

b3log

siyuan

CWE

CWE-918

Server-Side Request Forgery (SSRF)

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