CVE-2026-34585: SiYuan: Stored XSS in imported .sy.zip content leads to arbitrary command execution

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-31 · updated 2026-06-17
Weakness: CWE-79

Description

SiYuan is a personal knowledge management system. Prior to version 3.6.2, a vulnerability allows crafted block attribute values to bypass server-side attribute escaping when an HTML entity is mixed with raw special characters. An attacker can embed a malicious IAL value inside a .sy document, package it as a .sy.zip, and have the victim import it through the normal Import -> SiYuan .sy.zip workflow. Once the note is opened, the malicious attribute breaks out of its original HTML context and injects an event handler, resulting in stored XSS. In the Electron desktop client, this XSS reaches remote code execution because injected JavaScript runs with access to Node/Electron APIs. This issue has been patched in version 3.6.2.

Affected products

siyuan-note siyuan: before 3.6.2 — fixed in 3.6.2

How to fix

Upgrade to a fixed version: siyuan-note siyuan 3.6.2. Check the vendor advisory for mitigations.

References

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