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9.9
CVE-2026-66012: SiYuan lets unauthenticated users take administrator control
CVE-2026-66012 · published 2 months ago
Summary
If SiYuan is running a version older than 3.7.2 and the Publish feature is left open to anyone, an outsider can reach a management endpoint and read or change any file in the workspace. This includes planting malicious plugins that run with full privileges, effectively giving the attacker full administrator rights. Upgrade SiYuan to version 3.7.2 or later, and disable anonymous publishing or require authentication for the Publish service.
What to do
- Update siyuan-note siyuan to version 3.7.2 or later.
Affected software
| Vendor | Product | Affected versions |
|---|---|---|
| siyuan-note | siyuan | < 3.7.2 |
Original advisory text
SiYuan before v3.7.2 Unauthenticated Administrator Takeover via MCP
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.
References
- https://github.com/siyuan-note/siyuan/security/advisories/GHSA-cvhv-7xhj-xjp8 Vendor Advisory
- https://github.com/siyuan-note/siyuan/commit/c72ca4cd09019e5f64afdee8f8c6ec5ef34... Patch
- https://www.vulncheck.com/advisories/siyuan-before-unauthenticated-administrator... Vendor Advisory
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66012... Vendor Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2026-66012 Vendor Advisory
Severity
9.9
Critical
CVSS 3.1: 10.0 (NVD)
CVSS 4.0: 10.0 (NVD)
CVSS 4.0: 9.9 (OSV)
Exploitation
EPSS <1%
Type
CWE-862Missing Authorization
Timeline
Published25 Jul 2026
Updated27 Sep 2026
First seen25 Jul 2026
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