CVE-2026-56397: SiYuan - Remote Code Execution via Malicious Bazaar Package Metadata and README

Synopsis

This is a cross-site scripting (XSS) to remote code execution vulnerability in SiYuan, a note-taking application built on Electron. An unauthenticated attacker who can publish a malicious package to the Bazaar marketplace can inject arbitrary HTML and JavaScript into package metadata fields (displayName, description, README), which executes as OS-level commands when any user browses the marketplace, because Electron's nodeIntegration setting grants renderer pages direct access to Node.js APIs. Successful exploitation gives the attacker full remote code execution on the victim's machine. A patched-image rebuild at version 3.6.1 is available on HarborGuard for environments running an affected version.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The attacker must be able to publish a package to the Bazaar marketplace, which is reachable over the network, and the victim must browse the marketplace from a network-connected SiYuan instance.

• AuthenticationNot required

  No authentication or account privileges are required on the victim's side; anyone who browses the Bazaar marketplace is exposed.

• Victim interactionRequired

  A victim must open or browse the Bazaar marketplace page within SiYuan, making this a social-engineering vector where a malicious package must attract or be surfaced to the victim.

• Attack complexityDetail

  Exploitation is reliable and condition-free once the malicious package is published; no race conditions, memory layout knowledge, or special environmental factors are required.

Blast Radius

• The attacker executes arbitrary operating system commands on the victim's machine with the privileges of the SiYuan process, gaining a full foothold on the host.
• All files accessible to the running user (notes, credentials, SSH keys, browser session data) can be read and exfiltrated.
• The attacker can write or modify files on the host, including configuration files and application binaries reachable by the current user.
• The SiYuan process and any dependent services can be crashed or hijacked, disrupting availability for the affected user.