Auth bypass in Siyuan-Note Siyuan
CVE-2026-68586
SiYuan before v3.7.3 fails to apply publish-access filters to the getBacklinkDoc and getBackmentionDoc content endpoints (/api/ref/getBacklinkDoc and /api/ref/getBackmentionDoc). While the corresponding backlink list endpoints filter publish-forbidden documents, the content endpoints (gated only by CheckAuth) do not. A publish-mode reader — including an anonymous reader when publish Basic Auth is disabled — can call these endpoints directly with a publish-forbidden document's ID to retrieve its rendered DOM content and to determine whether the document references a given block (a reference-existence oracle).
Vulnerability class: Broken Access Control
EPSS: 0.002 (15.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N.
Affected products
- Siyuan-note Siyuan — versions 0, 3.7.3
Weakness classification (CWE)
References
- disclosure@vulncheck.com (vendor-advisory)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-68586?
- CVE-2026-68586 is a high-severity vulnerability in Siyuan-Note Siyuan, classified under Missing Authorization. CVSS score: 8.6/10. Published 2026-08-03.
- How severe is CVE-2026-68586?
- High severity. CVSS v3 base score is 8.6 out of 10.