CVE-2026-40107
MEDIUMDescription
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 <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.
How to fix
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 22% of all known CVEs.
References
Related Vulnerabilities
Other CWE-918 (Server-Side Request Forgery (SSRF)) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-21893 | High | 8.2 | 100% | KEV + Ransom | - |
| CVE-2021-40438 | Critical | 9.0 | 100% | KEV | Fix |
| CVE-2021-34473 | Critical | 9.1 | 100% | KEV + Ransom | Fix |
| CVE-2021-26855 | Critical | 9.1 | 100% | KEV + Ransom | Fix |
| CVE-2021-21985 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2022-41040 | High | 8.8 | 100% | KEV + Ransom | Fix |
Embed a live status badge for CVE-2026-40107
Markdown
[](https://tridentstack.com/cve/CVE-2026-40107)HTML
<a href="https://tridentstack.com/cve/CVE-2026-40107"><img src="https://tridentstack.com/cve/badge/CVE-2026-40107.svg" alt="CVE-2026-40107"></a>Find and fix vulnerabilities across your fleet
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Start freeThis product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-04-16.