CVE-2026-41421: SiYuan Desktop RCE via HTML Notification Abuse
The National Vulnerability Database has detailed CVE-2026-41421, a high-severity vulnerability (CVSS 8.8) affecting SiYuan, an open-source personal knowledge management system. Prior to version 3.6.5, SiYuan’s desktop application was susceptible to remote code execution due to improper handling of notification messages. The application rendered notification content as raw HTML within an Electron renderer.
Attackers could exploit this by sending a crafted msg value to the /api/notification/pushMsg endpoint. Because desktop builds of SiYuan’s Electron windows were configured with nodeIntegration: true, contextIsolation: false, and webSecurity: false, JavaScript embedded in these notifications could directly access Node.js APIs. This configuration allowed for a straightforward escalation from cross-site scripting (XSS) to full desktop code execution, bypassing typical browser security models.
This vulnerability is a critical reminder of the dangers of misconfigured Electron applications. The nodeIntegration: true setting essentially turns an XSS into a local code execution primitive. Defenders need to understand that the security context of Electron apps is fundamentally different from a standard web browser, especially when Node.js integration is enabled. The fix is available in SiYuan version 3.6.5.
What This Means For You
- If your organization or individual users rely on SiYuan for knowledge management, this is a critical patch. Immediately upgrade all SiYuan desktop installations to version 3.6.5 or later to mitigate CVE-2026-41421. Failing to do so leaves users vulnerable to remote code execution, which can lead to complete system compromise if an attacker can push a malicious notification.
Related ATT&CK Techniques
🛡️ Detection Rules
3 rules · 6 SIEM formats3 detection rules auto-generated for this incident, mapped to MITRE ATT&CK. Sigma YAML is free — export to any SIEM format via the Intel Bot.
CVE-2026-41421: SiYuan Desktop RCE via HTML Notification Abuse
title: CVE-2026-41421: SiYuan Desktop RCE via HTML Notification Abuse
id: scw-2026-04-24-ai-1
status: experimental
level: critical
description: |
Detects the execution of SiYuan.exe with specific Electron configurations that enable RCE via HTML notification abuse, as described in CVE-2026-41421. This rule targets the core vulnerability where raw HTML is rendered with elevated privileges.
author: SCW Feed Engine (AI-generated)
date: 2026-04-24
references:
- https://shimiscyberworld.com/posts/nvd-CVE-2026-41421/
tags:
- attack.execution
- attack.t1059.001
logsource:
category: process_creation
detection:
selection:
Image|endswith:
- 'SiYuan.exe'
CommandLine|contains:
- 'nodeIntegration: true'
- 'contextIsolation: false'
- 'webSecurity: false'
condition: selection
falsepositives:
- Legitimate administrative activity
Source: Shimi's Cyber World · License & reuse
Indicators of Compromise
| ID | Type | Indicator |
|---|---|---|
| CVE-2026-41421 | RCE | SiYuan desktop < 3.6.5 |
| CVE-2026-41421 | XSS | SiYuan desktop < 3.6.5 |
| CVE-2026-41421 | Code Injection | POST /api/notification/pushMsg with user-controlled 'msg' value |
| CVE-2026-41421 | Misconfiguration | Electron windows with nodeIntegration: true, contextIsolation: false, webSecurity: false in main.js |
Written by SCW Vulnerability Desk
Source & Attribution
| Source Platform | NVD |
| Channel | National Vulnerability Database |
| Published | April 24, 2026 at 22:17 UTC |
This content was AI-rewritten and enriched by Shimi's Cyber World based on the original source. All intellectual property rights remain with the original author.
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