Auth bypass in Siyuan-Note Siyuan
CVE-2026-74904
SiYuan before v3.7.4 is missing authorization checks in 17 block metadata/content endpoints in kernel/api/block.go (including getRefText, checkBlockExist, and getBlockBreadcrumb). These handlers are gated only by basic authentication (model.CheckAuth) and lack publish-access filtering, allowing anonymous publish-mode readers to disclose private block content-derived text, structural metadata, and existence information for arbitrary block IDs across the workspace.
Vulnerability class: Broken Access Control
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
Affected products
Weakness classification (CWE)
References
- disclosure@vulncheck.com (vendor-advisory)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-74904?
- CVE-2026-74904 is a high-severity vulnerability in Siyuan-Note Siyuan, classified under Missing Authorization. CVSS score: 7.5/10. Published 2026-08-18.
- How severe is CVE-2026-74904?
- High severity. CVSS v3 base score is 7.5 out of 10.