What is CVE-2026-66394?

CVE-2026-66394 is a high-severity vulnerability in Siyuan-note Siyuan, classified under Cross-site Scripting. CVSS score: 8.7/10. Published 2026-07-27.

How severe is CVE-2026-66394?

High severity. CVSS v3 base score is 8.7 out of 10.

XSS in Siyuan-note Siyuan

CVE-2026-66394

SiYuan before v3.7.3 contains stored and reflected cross-site scripting vulnerabilities in SVG sanitization that allows authenticated attackers to execute scripts by bypassing the HTML parser-based cleaner. Attackers can hide script tags w…

Vulnerability class: XSS (Cross-Site Scripting)

CVSS v3 metric

CVSS v3 base score 8.7 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N.

Affected products

Siyuan-note Siyuan — versions 0, 3.7.3

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

disclosure@vulncheck.com (vendor-advisory)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-66394?: CVE-2026-66394 is a high-severity vulnerability in Siyuan-note Siyuan, classified under Cross-site Scripting. CVSS score: 8.7/10. Published 2026-07-27.
How severe is CVE-2026-66394?: High severity. CVSS v3 base score is 8.7 out of 10.