CVE-2026-100637: 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 checkoutRepo endpoint that allows authenticated administrators to write JSON files outside the workspace. Attackers can supply a sessionID parameter containing directory traversal sequences to overwrite arbitrary JSON files in pre-existing kernel-writable directories outside workspace boundaries.

Affected products

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

Published 2026-09-26. Last modified 2026-10-05.