What is CVE-2026-66012?

CVE-2026-66012 is a critical-severity vulnerability in Siyuan-note Siyuan, classified under Missing Authorization. CVSS score: 10.0/10. Published 2026-07-25.

How severe is CVE-2026-66012?

Critical severity. CVSS v3 base score is 10.0 out of 10.

Auth bypass in Siyuan-note Siyuan

CVE-2026-66012

SiYuan before v3.7.2 contains a missing authorization vulnerability in the POST /mcp kernel endpoint, which is gated only by a general auth check (model.CheckAuth) with no admin-role or read-only enforcement. This exposes 31 MCP tools, inc…

Vulnerability class: Broken Access Control

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.

Affected products

Siyuan-note Siyuan — versions 0, 3.7.2

Weakness classification (CWE)

CWE-862 — Missing Authorization

References

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

Frequently asked questions

What is CVE-2026-66012?: CVE-2026-66012 is a critical-severity vulnerability in Siyuan-note Siyuan, classified under Missing Authorization. CVSS score: 10.0/10. Published 2026-07-25.
How severe is CVE-2026-66012?: Critical severity. CVSS v3 base score is 10.0 out of 10.