CVE-2026-66012 Details
Description
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, including a file tool with list/read/write/delete/rename/copy actions across the entire workspace. When the Publish server is enabled in anonymous mode (Conf.Publish.Enable=true and Conf.Publish.Auth.Enable=false), the Publish reverse proxy attaches an anonymous RoleReader JWT to proxied requests, allowing a remote unauthenticated attacker to reach /mcp. The attacker can read conf/conf.json to extract accessAuthCode, api.token, and cookieKey in plaintext, write arbitrary files in the workspace, and plant a plugin into data/plugins/ that executes with nodeIntegration:true and no contextIsolation on the next desktop launch, leading to administrator takeover.
A missing authorization vulnerability has been identified in SiYuan versions prior to 3.7.2. The issue resides in the POST /mcp kernel endpoint, which is only protected by a general authentication check, lacking specific admin-role or read-only enforcement. This vulnerability exposes 31 MCP tools, including a file management tool that allows listing, reading, writing, deleting, renaming, and copying files across the entire workspace. The vulnerability is exploited when the Publish server is enabled in anonymous mode, allowing a remote unauthenticated attacker to access the /mcp endpoint. The attacker can read the conf/conf.json file to extract sensitive information, write arbitrary files in the workspace, and install a malicious plugin that executes with elevated privileges on the next desktop launch, leading to unauthorized administrative access.
Users should update to SiYuan version 3.7.2 or later, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jul 25, 2026CISA-ADP
Assessed Jul 27, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/siyuan-note/siyuan/security/advisories/GHSA-cvhv-7xhj-xjp8 | CISA-ADP | AdvisoryExploitTechnical AnalysisVendor |
| https://github.com/siyuan-note/siyuan/commit/c72ca4cd09019e5f64afdee8f8c6ec5ef34858db | [email protected] | Source CodeVendor |
| https://github.com/siyuan-note/siyuan/security/advisories/GHSA-cvhv-7xhj-xjp8 | [email protected] | AdvisoryExploitTechnical AnalysisVendor |
| https://www.vulncheck.com/advisories/siyuan-before-unauthenticated-administrator-takeover-via-mcp | [email protected] | AdvisoryBundle |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-862 | Missing Authorization | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| SiYuan | >= 0, < 3.7.2 |
CPE
Remediation
| |
Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 17, 2026 | CVE Modified | [email protected] |
| Sep 17, 2026 | CVE Modified | CISA-ADP |
| Jul 27, 2026 | CVE Modified | CISA-ADP |
| Jul 25, 2026 | New CVE Received | [email protected] |