---
cve: "CVE-2026-100639"
severity: "HIGH"
cvss: 8.6
epss: "22.4%"
vendor: "siyuan-note"
kev: false
exploited: false
published: "2026-09-26 14:16:45"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-27T07:03:30+02:00"
---

# CVE-2026-100639

> 8.6 HIGH · 🧪 PoC

## Beschreibung

SiYuan v3.8.3 fails to HTML-escape the data-subtype attribute when generating gutter-button markup (app/src/protyle/gutter/button.ts, assigned via innerHTML in app/src/protyle/gutter/index.ts) from content pasted as plain-text Markdown containing a Kramdown inline attribute list (IAL). Because the shared Lute renderer parses Kramdown IAL from text/plain input, an attacker-supplied Markdown snippet using entity-encoded quotes in data-subtype breaks out of the attribute value when the gutter markup is re-parsed by the browser, injecting additional attributes such as autofocus and onfocus. If a victim pastes the crafted Markdown and the affected gutter control receives focus, the injected handler executes; in the Electron desktop application, where the main BrowserWindow enables Node integration and disables context isolation, this results in JavaScript execution with renderer Node.js privileges (remote code execution). Fixed in v3.8.4.

## CVSS-Vektor

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

| 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-2cmm-9x9j-rvff>
- <https://www.vulncheck.com/advisories/siyuan-before-3.8.4-cross-site-scripting-via-kramdown-ial>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-100639) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_