CVE-2026-40259: SiYuan: Publish Reader Can Arbitrarily Delete Attribute View Files via removeUnusedAttributeView API

Severity: high (CVSS 8.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-16 · updated 2026-06-17
Weakness: CWE-285

Description

SiYuan is an open-source personal knowledge management system. In versions 3.6.3 and below, the /api/av/removeUnusedAttributeView endpoint is protected only by generic authentication that accepts publish-service RoleReader tokens. The handler passes a caller-controlled id directly to a model function that unconditionally deletes the corresponding attribute view file from the workspace without verifying that the caller has write privileges or that the target attribute view is actually unused. An authenticated publish-service reader can permanently delete arbitrary attribute view definitions by extracting publicly exposed data-av-id values from published content, causing breakage of database views and workspace rendering until manually restored. This issue has been fixed in version 3.6.4.

Affected products

siyuan-note siyuan: before 3.6.4 — fixed in 3.6.4

How to fix

Upgrade to a fixed version: siyuan-note siyuan 3.6.4. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-40259 or the next vulnerability affects your stack