What’s Vulnerable › Vulnerabilities

CVE-2026-66394: SiYuan before v3.7.3 Stored and Reflected XSS via SVG Sanitizer Bypass

• Severity: high (CVSS 8.7 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-27 · updated 2026-10-24
• Weakness: CWE-79

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.

Affected products

• siyuan-note siyuan: before 3.7.3 — fixed in 3.7.3

How to fix

Upgrade to a fixed version: siyuan-note siyuan 3.7.3. Check the vendor advisory for mitigations.

References

• https://github.com/siyuan-note/siyuan/security/advisories/GHSA-99rq-75j6-5j9f
• https://www.vulncheck.com/advisories/siyuan-before-stored-and-reflected-xss-via-svg-sanitizer-bypass
• https://github.com/siyuan-note/siyuan/security/advisories/GHSA-99rq-75j6-5j9f

Get alerted when CVE-2026-66394 or the next vulnerability affects your stack