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CVE-2026-66012— SiYuan before v3.7.2 Unauthenticated Administrator Takeover via MCP

Quick assessment

Affected
siyuan-note siyuan
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

SiYuan是SiYuan团队开源的一个个人知识管理系统。 SiYuan 3.7.2之前版本存在授权问题漏洞，该漏洞源于POST /mcp内核端点缺少授权验证，仅通过通用检查未强制管理员或只读角色，当发布服务器以匿名模式启用时，远程未认证攻击者可访问/mcp端点，读取配置文件获取明文凭据，写入任意文件并植入插件，导致管理员接管。

CVSS 10.0 · Critical EPSS 0.76% · P53

Affected Version Matrix 2

VendorProduct Version RangeStatus
siyuan-note siyuan < 3.7.2 affected
3.7.2 unaffected
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I. Basic Information for CVE-2026-66012

Vulnerability Information
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Vulnerability Title
SiYuan before v3.7.2 Unauthenticated Administrator Takeover via MCP
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
授权机制缺失
Source: CVE Program / CVE List V5
Vulnerability Title
SiYuan 授权问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
SiYuan是SiYuan团队开源的一个个人知识管理系统。 SiYuan 3.7.2之前版本存在授权问题漏洞，该漏洞源于POST /mcp内核端点缺少授权验证，仅通过通用检查未强制管理员或只读角色，当发布服务器以匿名模式启用时，远程未认证攻击者可访问/mcp端点，读取配置文件获取明文凭据，写入任意文件并植入插件，导致管理员接管。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
siyuan-note siyuan 0 ~ 3.7.2 -

II. Public POCs for CVE-2026-66012

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 8135 chars
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III. Intelligence Information for CVE-2026-66012

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Patches & Fixes for CVE-2026-66012 (1)

Vendor Advisories for CVE-2026-66012 (2)

IV. Related Vulnerabilities

Same product: siyuan
Same vendor: siyuan-note
Same weakness: CWE-862

V. Comments for CVE-2026-66012

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