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
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.005 (40.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 40.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.001
Affected products
Weakness classification (CWE)
References
- github.com/siyuan-note/siyuan/security/advisories/GHSA-4vpg-gwqq-w44c (vendor-advisory)
- www.vulncheck.com/advisories/siyuan-before-missing-authorization-via-block-api (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.