---
cve: "CVE-2026-100634"
severity: "MEDIUM"
cvss: 5.3
epss: "0.5%"
vendor: "siyuan-note"
kev: false
exploited: false
published: "2026-09-26 14:16:44"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-10-01T03:07:43+02:00"
---

# CVE-2026-100634

> 5.3 MEDIUM · 🧪 PoC

## Beschreibung

SiYuan before v3.8.4 does not validate the sender or restrict recipients in the 'siyuan-send-windows' IPC handler of the Electron main process (app/electron/main.js). The handler ignores event.sender and forwards any received payload to every BrowserWindow returned by BrowserWindow.getAllWindows(), including windows belonging to other opened workspaces. A renderer connected to an attacker-controlled remote kernel can therefore send {cmd: "lockscreenByMode"} and have it delivered across the workspace boundary; a sibling workspace window whose lockScreenMode is set to 1 invokes lockScreen(). Repeated messages allow the remote workspace to repeatedly lock unrelated local workspace windows, causing a limited denial of service. No confidentiality, integrity, or code-execution impact was observed.

## CNA-Record (Kanon, cvelistV5)

- CNA: **VulnCheck**
- State: PUBLISHED
- Stand: 2026-09-30 13:01:30
- CNA-CVSS: **5.3** (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L`)

## CISA-Anreicherung (vulnrichment/ADP)

- CISA-SSVC (Coordinator, v2.0.3):
  - Exploitation: **poc**
  - Automatable: **no**
  - Technical Impact: **partial**

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- 9f775e8a12daef8255556097396f9b2739078892 (Commit)

## Referenzen

- <https://github.com/siyuan-note/siyuan/security/advisories/GHSA-wxp7-xpq8-8xpm>
- <https://github.com/siyuan-note/siyuan/commit/8641553a1f07374001902d3ce773285db1292b2d>
- <https://www.vulncheck.com/advisories/siyuan-before-3.8.4-missing-authorization-via-siyuan-send-windows>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-100634) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI WID (CSAF)_