CVE-2026-74800: Siyuan-Note Siyuan

Critical severity, CVSS 9.0. EPSS: 0.4% chance of exploitation in the next 30 days.

SiYuan before v3.7.4 fails to set Content-Disposition and X-Content-Type-Options headers when serving arbitrary file assets, allowing stored cross-site scripting attacks. Authenticated attackers can upload HTML files as assets and execute scripts with full kernel API access when the workspace owner opens the asset link.

Affected products

• Siyuan-Note Siyuan: before 3.7.4 (fixed in 3.7.4)

Published 2026-08-17. Last modified 2026-08-26.