---
cve: "CVE-2026-66012"
severity: "CRITICAL"
cvss: 10.0
epss: "44%"
vendor: "siyuan-note"
kev: false
exploited: false
published: "2026-07-25 11:17:19"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-08-31T21:28:10+02:00"
---

# CVE-2026-66012

> 10.0 CRITICAL · 🧪 PoC

## Beschreibung

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.

## CVSS-Vektor

```
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |

## Patch verfügbar (OSV)

- 726dae1d518927f70ea609bc146288b9aa95e366 (Commit)

## Referenzen

- <https://github.com/siyuan-note/siyuan/security/advisories/GHSA-cvhv-7xhj-xjp8>
- <https://github.com/siyuan-note/siyuan/commit/c72ca4cd09019e5f64afdee8f8c6ec5ef34858db>
- <https://www.vulncheck.com/advisories/siyuan-before-unauthenticated-administrator-takeover-via-mcp>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-66012) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_