CVE-2026-100640: Siyuan-Note Siyuan

Medium severity, CVSS 4.7. EPSS: 0.2% chance of exploitation in the next 30 days.

SiYuan before v3.8.4 contains an authorization omission in the siyuan-get IPC handler that allows remote-kernel renderers to access native clipboard formats by invoking clipboardReadMathML, clipboardReadOffice, and clipboardReadWPS commands with matching plaintext. Attackers controlling remote renderer content can obtain MathML formulas, Office bytes, and WPS bytes from local clipboard during user-mediated paste operations.

Affected products

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

Published 2026-09-26. Last modified 2026-10-08.