SiYuan Vulnerable to Arbitrary File Read in Desktop Publish Service

The vulnerability lies within the /api/lute/html2BlockDOM endpoint, which handles HTML pasting. An attacker can leverage this by crafting malicious HTML containing file:// links pointing to sensitive local files. The SiYuan kernel then copies these files into the workspace assets directory without proper path validation. Crucially, the /assets/*path endpoint, accessible with authentication, allows the attacker to retrieve these copied files via a simple GET request. This enables the exfiltration of sensitive data, including configuration files, credentials, or other confidential information stored on the system. The blast radius extends to any data accessible by the user running the SiYuan desktop application.

Users of SiYuan who handle sensitive data, particularly those who frequently paste content from external sources, are at significant risk. Organizations using SiYuan in shared hosting environments or with legacy configurations lacking robust access controls are especially vulnerable.

• linux / server:

journalctl -u siyuan -g "html2BlockDOM"

• generic web:

curl -I 'http://<siyuan_server>/api/lute/html2BlockDOM?file:///etc/passwd' # Check for file access

• generic web:

 grep -r 'file://' /var/log/nginx/access.log # Look for file:// URLs in access logs

1. 2026-03-17Disclosure

   disclosure

1. Reserviert2026-03-17
2. Veröffentlicht2026-03-17
3. Geändert2026-03-30
4. EPSS aktualisiert2026-03-27

The primary mitigation is to upgrade to SiYuan version 3.6.1 or later, which includes the necessary path validation fixes. If upgrading immediately is not feasible, consider restricting access to the /assets/*path endpoint to authenticated users only, although this does not fully address the underlying vulnerability. Implement a Web Application Firewall (WAF) rule to block requests containing file:// URLs in the /api/lute/html2BlockDOM endpoint. Monitor SiYuan logs for unusual file access patterns or attempts to access files in the workspace assets directory. There are no specific Sigma or YARA rules available at this time, but monitoring file creation events in the workspace directory is recommended.