What is CVE-2026-74902?

CVE-2026-74902 is a high-severity vulnerability in Siyuan-Note Siyuan, classified under Cross-site Scripting. CVSS score: 8.6/10. Published 2026-08-18.

How severe is CVE-2026-74902?

High severity. CVSS v3 base score is 8.6 out of 10.

XSS in Siyuan-Note Siyuan

CVE-2026-74902

SiYuan before v3.7.4 contains a cross-site scripting vulnerability in the file upload validation flow that fails to escape filenames before inserting them into HTML via insertAdjacentHTML. Attackers can craft a malicious filename containing script payloads that execute with full OS command access when a user drags, drops, or pastes the file into the editor.

Vulnerability class: XSS (Cross-Site Scripting)

CVSS v3 metric

CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.

Affected products

Siyuan-note Siyuan

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

disclosure@vulncheck.com (vendor-advisory)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-74902?: CVE-2026-74902 is a high-severity vulnerability in Siyuan-Note Siyuan, classified under Cross-site Scripting. CVSS score: 8.6/10. Published 2026-08-18.
How severe is CVE-2026-74902?: High severity. CVSS v3 base score is 8.6 out of 10.