Junglewise Threat Intelligence

CVE-2026-66395: SiYuan Desktop reflected XSS to RCE in bazaar plugin handler

CVE-2026-66395 · Severity: critical · CVSS 9.6 · Published 2026-07-27

Executive brief

SiYuan, a personal knowledge management and note-taking application, is vulnerable to a security flaw that allows attackers to take complete control of a user's computer. By tricking a user into clicking a specially crafted link (starting with 'siyuan://'), an attacker can execute malicious commands on the victim's operating system. This could lead to the theft of private notes, data deletion, or the installation of malware.

Technical details

A reflected cross-site scripting (XSS) vulnerability exists in the SiYuan desktop application's handling of the 'siyuan://' protocol. The application fails to sanitize the plugin name segment in the 'bazaar/plugins/<name>/readme' path, which is decoded and passed to the 'showMessage' function. This function uses 'insertAdjacentHTML' to render the input in an Electron renderer configured with 'nodeIntegration: true' and 'contextIsolation: false'. An attacker can leverage this to execute arbitrary Node.js commands and achieve Remote Code Execution (RCE) on the host OS. The vulnerability is patched in version 3.7.2.

Affected products

  • siyuan-note SiYuan < 3.7.2

Timeline

  • 2026-07-13: advisory: GitHub Security Advisory published
  • 2026-07-27: disclosed: NVD publication date
  • 2026-07-27: patched: Vendor released version 3.7.2 to address the issue

References

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