CVE-2026-92985 in SiYuan
Summary
by MITRE • 09/17/2026
SiYuan versions before 3.8.4 fail to escape bookmark labels imported from notebook files when rendering them in the dock tree. Attackers can craft malicious .sy notebook files with unescaped HTML in bookmark attributes that execute scripts in the Electron renderer with access to child_process for command execution.
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Analysis
by VulDB Data Team • 09/17/2026
The vulnerability identified in SiYuan versions prior to 3.8.4 represents a critical security flaw rooted in improper input validation and output encoding within the application's notebook parsing logic. Specifically, when users import or open .sy notebook files that contain bookmark entries with HTML content in their labels, the software fails to properly escape these characters before rendering them in the dock tree interface. This failure allows raw HTML tags embedded within the bookmark metadata to be interpreted directly by the browser-based renderer rather than being treated as plain text data. The core technical deficiency lies in the absence of robust sanitization mechanisms for user-supplied content during the import process, which violates fundamental principles of secure coding regarding untrusted data handling.
From a technical perspective, this flaw constitutes an instance of Cross-Site Scripting (XSS), specifically categorized under CWE-79: Improper Neutralization of Input During Web Page Generation in many security frameworks. Because SiYuan is built on the Electron framework, which combines Chromium for rendering and Node.js for backend operations, the implications are significantly more severe than traditional web-based XSS attacks. In a standard browser environment, an XSS attack might allow an attacker to steal cookies or session tokens. However, within the Electron architecture, the renderer process often has access to Node.js APIs if certain security configurations like contextIsolation and nodeIntegration are not strictly enforced or bypassed through specific vector exploitation techniques.
The operational impact of this vulnerability is substantial because it enables Remote Code Execution (RCE). By crafting a malicious .sy file containing script tags within bookmark labels, an attacker can inject JavaScript code that executes in the renderer process. If the application's security context permits access to Node.js modules from the renderer, or if specific Electron APIs are exposed without adequate restrictions, this injected script can invoke child_process functions. This capability allows the execution of arbitrary operating system commands on the victim's machine with the privileges of the user running SiYuan. Consequently, an attacker could potentially install malware, exfiltrate sensitive data stored locally by the application, or use the compromised device as a pivot point for further network attacks.
This attack vector aligns closely with MITRE ATT&CK techniques related to client-side code injection and command execution via local applications. It highlights the risks associated with rich text editors and note-taking platforms that process complex file formats containing embedded media or metadata. The vulnerability underscores the importance of strict content security policies (CSP) within Electron applications, ensuring that renderer processes are isolated from backend capabilities unless explicitly required for specific functionalities. Furthermore, it emphasizes the need for rigorous input sanitization at all stages of data ingestion, particularly when handling files created by external sources which may not be trusted.
To mitigate this vulnerability and similar risks in future versions, developers must implement comprehensive output encoding specifically targeting HTML contexts within the dock tree rendering logic. All user-supplied content derived from imported notebook files should undergo strict sanitization to strip or escape potentially dangerous characters such as angle brackets, quotes, and script delimiters before they are inserted into the DOM. Additionally, enforcing a robust Content Security Policy that restricts inline script execution and limits access to Node.js APIs in renderer processes is essential for preventing code injection attacks from escalating to remote command execution. Users of affected versions should immediately upgrade to version 3.8.4 or later where these security controls have been strengthened. Until an update can be applied, users are advised to avoid opening .sy files from untrusted sources and to review the source content of notebooks before importing them into the application environment.