CVE-2026-56397: SiYuan Bazaar Marketplace RCE Vulnerability

CVE-2026-56397 Overview

CVE-2026-56397 is a Cross-Site Scripting (XSS) vulnerability in SiYuan, a self-hosted personal knowledge management application, affecting versions prior to v3.6.1. The flaw exists in the Bazaar marketplace component, which fails to sanitize package metadata and README content. Malicious package authors can inject arbitrary HTML and JavaScript through the displayName, description, or README fields. Because SiYuan runs on Electron with nodeIntegration enabled, the injected JavaScript escalates from browser-context XSS to full remote code execution on the host operating system. The vulnerability is categorized under CWE-79.

Critical Impact
Any user browsing the SiYuan Bazaar marketplace can be compromised by a malicious package, resulting in arbitrary OS command execution through the Electron runtime.

Affected Products

SiYuan versions prior to v3.6.1
SiYuan Electron desktop application (Windows, macOS, Linux)
SiYuan Bazaar marketplace package consumers

Discovery Timeline

2026-06-21 - CVE-2026-56397 published to NVD
2026-06-24 - Last updated in NVD database

Technical Details for CVE-2026-56397

Vulnerability Analysis

The vulnerability resides in SiYuan's Bazaar marketplace rendering pipeline. Bazaar is the in-application package repository where users browse community plugins, themes, templates, and icon sets. When SiYuan fetches package listings, it renders untrusted metadata fields and README documents directly into the application's DOM without sanitization. An attacker publishes a package containing a crafted displayName, description, or README payload. When any user views the package, the injected JavaScript executes in the SiYuan window context. Refer to the GitHub Security Advisory GHSA-v3mg-9v85-fcm7 and the VulnCheck Remote Code Execution Advisory for technical specifics.

Root Cause

The root cause is missing output encoding and HTML sanitization when rendering Bazaar package fields. SiYuan trusts marketplace-supplied content and inserts it into the renderer using methods that interpret HTML markup. Combined with Electron's nodeIntegration: true configuration, this transforms a standard stored XSS into remote code execution. The renderer process exposes the Node.js require function, allowing injected scripts to load modules such as child_process and invoke exec to run arbitrary OS commands.

Attack Vector

Exploitation requires the attacker to publish or modify a package in the Bazaar repository and the victim to view that package within the SiYuan client. User interaction is limited to opening the Bazaar tab and selecting the malicious package. No authentication is required by the victim. Once the payload executes, the attacker inherits the privileges of the SiYuan process, enabling file theft, credential harvesting, persistence installation, or lateral movement.

No verified proof-of-concept code is available in the referenced advisories. See the VulnCheck advisory for additional detail on the exploitation chain.

Detection Methods for CVE-2026-56397

Indicators of Compromise

Unexpected child processes spawned by the SiYuan Electron binary, such as cmd.exe, powershell.exe, /bin/sh, or bash.
Outbound network connections from SiYuan to non-Bazaar domains shortly after a user opens the marketplace.
New files written to user profile, startup, or autostart directories after Bazaar browsing activity.
Bazaar package metadata containing <script>, onerror=, or javascript: substrings in fetched JSON or README files.

Detection Strategies

Monitor process lineage for SiYuan parenting shell or scripting interpreters, which is anomalous for a notes application.
Inspect HTTP responses from Bazaar mirrors for HTML-bearing characters in package metadata fields where plain text is expected.
Alert on Electron applications with nodeIntegration enabled executing require('child_process') patterns in renderer telemetry.

Monitoring Recommendations

Track SiYuan version inventory across endpoints and flag installations below v3.6.1.
Capture endpoint command-line telemetry to correlate SiYuan-initiated execution with marketplace access events.
Review DNS and proxy logs for connections to attacker-controlled domains referenced in package README links.

How to Mitigate CVE-2026-56397

Immediate Actions Required

Upgrade all SiYuan installations to v3.6.1 or later without delay.
Instruct users to avoid browsing the Bazaar marketplace on vulnerable versions until patched.
Audit recently installed Bazaar packages and remove any of unknown provenance.
Restrict outbound network access from endpoints running SiYuan to limit post-exploitation impact.

Patch Information

The SiYuan maintainers addressed the issue in version v3.6.1. The fix is documented in the GitHub Security Advisory GHSA-v3mg-9v85-fcm7. Administrators should download the latest release from the official SiYuan distribution channels and verify the installed version after deployment.

Workarounds

Disable or block access to the Bazaar marketplace feature within SiYuan until patching is complete.
Apply application allowlisting to prevent SiYuan from spawning shell interpreters and scripting hosts.
Run SiYuan under a least-privilege user account to reduce the blast radius of renderer-process compromise.

bash

# Verify the installed SiYuan version on Linux/macOS
siyuan --version

# Example: block SiYuan from launching shells via AppArmor/SELinux or EDR policy
# (pseudocode policy fragment)
deny process siyuan exec /bin/sh
deny process siyuan exec /bin/bash
deny process siyuan exec /usr/bin/osascript