Auth bypass in Siyuan-Note Siyuan
CVE-2026-72812
SiYuan versions before v3.7.4 contain a missing authorization vulnerability in the /api/ref/refreshBacklink endpoint that allows anonymous readers to trigger persistent server-side writes. Attackers can invoke the endpoint with an attacker-controlled block ID to flush transaction queues, scan all references globally, and enqueue database writes, bypassing read-only protections and enabling resource amplification attacks.
Vulnerability class: Broken Access Control
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L.
Affected products
- Siyuan-note Siyuan — versions 0, 3.7.4
Weakness classification (CWE)
References
- disclosure@vulncheck.com (vendor-advisory)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-72812?
- CVE-2026-72812 is a medium-severity vulnerability in Siyuan-Note Siyuan, classified under Missing Authorization. CVSS score: 6.5/10. Published 2026-08-14.
- How severe is CVE-2026-72812?
- Medium severity. CVSS v3 base score is 6.5 out of 10.