CVE-2026-87811: Siyuan-Note Siyuan

High severity, CVSS 7.3. EPSS: 0.4% chance of exploitation in the next 30 days.

SiYuan before v3.8.2 inserts persisted notebook template paths into HTML input value attributes without proper attribute encoding. Attackers can craft malicious template paths that break out of the attribute context and execute JavaScript when a victim opens notebook configuration, enabling same-origin API requests and application state manipulation.

Affected products

• Siyuan-Note Siyuan: before 3.8.2 (fixed in 3.8.2)

Published 2026-09-09. Last modified 2026-09-09.