Is CVE-2026-66394 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-66394?

CVE-2026-66394 has a CVSS v3 severity of HIGH (8.7).

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CVE-2026-66394

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.