CVE-2026-100636: Siyuan-Note Siyuan

High severity, CVSS 7.6. EPSS: 0.5% chance of exploitation in the next 30 days.

SiYuan versions before v3.8.4 contain a path traversal vulnerability in the exportBrowserHTML endpoint that allows authenticated administrators to write arbitrary HTML content to index.html outside the workspace directory. Attackers can supply a folder parameter with directory traversal sequences to escape the export directory and overwrite index.html in any pre-existing kernel-writable location, enabling stored XSS or workspace defacement.

Affected products

• Siyuan-Note Siyuan: before 3.8.4 (fixed in 3.8.4)

Published 2026-09-26. Last modified 2026-09-28.