SiYuan EUVD-2026-30354

User must actively open the Bazaar marketplace interface within the SiYuan desktop application and view a package listing containing the malicious metadata payload. The vulnerability affects only the desktop Electron application, not web-hosted or mobile instances, because exploitation requires the nodeIntegration: true and contextIsolation: false Electron configuration present in desktop builds. Attack complexity is high because the attacker must either compromise the official Bazaar package feed infrastructure, convince administrators to add a malicious third-party marketplace source, or register a seemingly legitimate package on the official marketplace that passes initial review. Default SiYuan installations are exploitable if users browse the marketplace, but exploitation is limited by the need for victim interaction with the specific malicious package entry rather than passive background exploitation.

CVSS 8.3 (High) accurately reflects the severity given the code execution outcome, though the vector string reveals important risk-limiting factors. Attack vector is Network (AV:N) but attack complexity is High (AC:H), requiring the attacker to craft a malicious package and publish it to the Bazaar marketplace or manipulate the feed URL. User interaction is Required (UI:R) - victims must actively browse the marketplace and view the malicious package entry. Scope is Changed (S:C), meaning the payload escapes the application context to the underlying OS. No EPSS data provided, no CISA KEV listing, and no public proof-of-concept identified, suggesting this remains a theoretical risk rather than actively exploited threat. The GitHub Security Advisory (GHSA-x6wf-w2rg-2gw9) confirms vendor acknowledgment. Real-world exploitation requires either compromising the official Bazaar feed infrastructure or social engineering users to add malicious third-party marketplace sources. For organizations running SiYuan 2.1.12-3.6.x, this is a critical upgrade priority despite the attack complexity, as successful exploitation yields full host compromise equivalent to running arbitrary executables with the user's privileges.

An attacker publishes a malicious package to the SiYuan Bazaar marketplace (or compromises an existing package) with specially crafted author metadata containing JavaScript payload. When a SiYuan user browses the marketplace to discover plugins or themes, the application renders the malicious metadata without HTML escaping, executing the payload in the Electron context. Because nodeIntegration is enabled, the payload calls require('child_process').exec() to download and execute a second-stage implant, establishing persistent access to the victim's workstation with full user privileges. No public proof-of-concept code has been identified, but the technical details in the security advisory provide sufficient information for capable attackers to develop working exploits.