CVE-2026-31807: b3log Siyuan

Medium severity, CVSS 6.1. EPSS: 0.5% chance of exploitation in the next 30 days.

SiYuan is a personal knowledge management system. Prior to 3.5.10, SiYuan's SVG sanitizer (SanitizeSVG) blocks dangerous elements (<script>, <iframe>, <foreignobject>) and removes on* event handlers and javascript: in href attributes. However, it does NOT block SVG animation elements (<animate>, <set>) which can dynamically set attributes to dangerous values at runtime, bypassing the static sanitization. This allows an attacker to inject executable JavaScript into the unauthenticated /api/icon/getDynamicIcon endpoint (type=8), creating a reflected XSS. This is a bypass of the fix for CVE-2026-29183 (fixed in v3.5.9). This vulnerability is fixed in v3.5.10.

Affected products

• b3log Siyuan: before 3.5.10 (fixed in 3.5.10)

Published 2026-03-10. Last modified 2026-06-17.