CVE-2026-66394
SiYuan before v3.7.3 Stored and Reflected XSS via SVG Sanitizer Bypass
- State
- Published
- Severity
- 9.3 Critical
- Published
- Jul 27, 2026
- Updated
- Oct 8, 2026
- Reserved
- Jul 26, 2026
Description
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 within desc, style, or noscript elements which the HTML parser treats as raw text but browsers interpret as executable SVG content when served as image/svg+xml, enabling script execution in the application origin.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 9.3 Critical | CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N | VulnCheck |
| 3.1 | 8.7 High | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N | VulnCheck |
Weaknesses
- CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Products
| Product | Versions |
|---|---|
siyuansiyuan-note |
|
References
- GitHub Security Advisory (GHSA-99rq-75j6-5j9f)vendor-advisory
- VulnCheck Advisory: SiYuan before v3.7.3 Stored and Reflected XSS via SVG Sanitizer Bypassthird-party-advisory
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