EUVD-2026-17687
GHSA-73g7-86qr-jrg3
CVSS Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
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Description
SiYuan is a personal knowledge management system. From version 3.6.0 to before version 3.6.2, the SanitizeSVG function introduced in version 3.6.0 to fix XSS in the unauthenticated /api/icon/getDynamicIcon endpoint can be bypassed by using namespace-prefixed element names such as <x:script xmlns:x="http://www.w3.org/2000/svg">. The Go HTML5 parser records the element's tag as "x:script" rather than "script", so the tag check passes it through. The SVG is served with Content-Type: image/svg+xml and no Content Security Policy; when a browser opens the response directly, its XML parser resolves the prefix to the SVG namespace and executes the embedded script. This issue has been patched in version 3.6.2.
Analysis
Cross-site scripting (XSS) in SiYuan personal knowledge management system versions 3.6.0-3.6.1 allows remote attackers to execute arbitrary JavaScript via the unauthenticated /api/icon/getDynamicIcon endpoint by bypassing SVG sanitization using XML namespace-prefixed element names. The vulnerability exploits a parser inconsistency where Go's HTML5 parser treats 'x:script' as a distinct tag while browsers' XML parsers resolve the namespace prefix to execute the script. …
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Remediation
Within 24 hours: inventory all SiYuan deployments and versions in use; restrict network access to the /api/icon/getDynamicIcon endpoint via firewall or WAF rules. Within 7 days: evaluate migration to SiYuan 3.6.2 or later when released; if unavailable, disable dynamic icon functionality or isolate affected instances to air-gapped environments. …
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