External risk intelligence

SiYuan Metadata Injection Allows Stored Cross-Site Scripting and Remote Code Execution.

CVE advisorySeverity: CRITICAL (CVSS 9.4)

CVE-2026-73042

SiYuan is a local-first personal knowledge management application typically running as a desktop client or a self-hosted private note-taking tool. The vulnerability requires user interaction to open specific menus within the local application interface, making public internet-facing exploitation unlikely.

Cross-site Scripting

Halo Surface Signal: 1 out of 5 — much less likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A vulnerability in SiYuan's handling of database menu metadata could allow script execution when users interact with specific menus. This occurs when an attacker injects malicious markup through field descriptions or names, potentially leading to arbitrary code execution due to Electron's configuration.

Unescaped metadata can run script in user menus.
Confirms exposure is unlikely for most.
Verify if this tool is used internally.

Attack Path

How an attacker could exploit the issue

An attacker could inject malicious code into a SiYuan database by describing a field with specially crafted HTML that includes script execution. This script could then be triggered when a user opens a group, views, or edits a field within the application. If the application is configured insecurely, this could lead to the execution of arbitrary code on the user's system.

Requires authenticated access and user interaction.
Triggered by opening specific application menus.
Risk of arbitrary code execution.

Live Threat

Current exploitation, exposure, and threat context

When users open specific menus in SiYuan, specially crafted markup in field descriptions or names could execute script, potentially reaching Node built-ins when supported by the advisory.

Sensitive metadata could be exposed.
Malicious scripts could run in menus.
Application control may be compromised.

Operational Fix

Recommended remediation, mitigation, and detection steps

The SiYuan application's vulnerability in handling database menu metadata requires careful ownership and triage by teams responsible for the application and its underlying platform. The first practical step is to identify all instances of SiYuan, determine their exposure and criticality, and then assign ownership for remediation.

Application owners should lead remediation efforts.
Verify if the application is externally accessible.
Plan maintenance for identified instances.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is SiYuan?

SiYuan is a local-first personal knowledge management system designed for note-taking and organizing information. It functions as a desktop client or a self-hosted private tool, allowing users to build structured databases and link content. Because it is built on Electron, it packages web technologies into a standalone application that can access system-level capabilities, which is a core component of this security concern.

What does CWE-79 mean in the context of CVE-2026-73042?

CWE-79 is the weakness class for Cross-Site Scripting (XSS). In this vulnerability, the software fails to properly sanitize or escape metadata found in database menus. When the application renders this metadata as HTML, it treats the attacker's injected text as executable code rather than plain text. Because the app uses an insecure Electron configuration, this script can break out of the application's sandbox to execute arbitrary commands on your computer.

How is this vulnerability triggered?

An attacker must successfully inject malicious markup into field names or descriptions within a SiYuan database. The payload does not trigger automatically; it only executes when a user interacts with the compromised data by opening a group, viewing a record, or editing a field menu. Simply storing the malicious data in the database is not enough to execute the code; the application must render the UI components that contain the tainted metadata.

Is my instance of SiYuan at risk?

Halo Surface Signal indicates that wide-scale exploitation via the public internet is very unlikely. SiYuan is typically deployed as a local client or a private self-hosted tool, meaning an attacker usually needs prior access to the database or the ability to share a malicious file with you to trigger the flaw. While the risk is lower than an internet-facing web server, you should still evaluate if your instance stores untrusted or shared data.

How do I respond to this threat?

Your first step is to identify all instances of SiYuan running in your environment. Once located, confirm if these instances are used to store data shared between multiple users or imported from untrusted sources, as these are the most common vectors for metadata injection. Prioritize updating the application to the latest version to apply the vendor's security patches and restrict the use of shared databases until you have verified the integrity of the information.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.