Information disclosure in Siyuan-Note Siyuan
CVE-2026-100640
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.
Vulnerability class: Information Disclosure
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.002 (15.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 15th percentile — 15.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.001
Affected products
Weakness classification (CWE)
References
- GitHub Security Advisory (GHSA-mjmm-hgmc-m7qf) (vendor-advisory)
- VulnCheck Advisory: SiYuan before v3.8.4 Clipboard Data Disclosure via IPC (third-party-advisory)
Frequently asked questions
- What is CVE-2026-100640?
- CVE-2026-100640 is a medium-severity vulnerability in Siyuan-Note Siyuan, classified under Information Disclosure. CVSS score: 4.7/10. Published 2026-09-26.
- How severe is CVE-2026-100640?
- Medium severity. CVSS v3 base score is 4.7 out of 10.