SiYuan up to 3.6.3 removeUnusedAttributeView ID improper authorization

Summaryinfo

A vulnerability, which was classified as critical, has been found in SiYuan up to 3.6.3. Affected by this vulnerability is an unknown functionality of the file /api/av/removeUnusedAttributeView. The manipulation of the argument ID leads to improper authorization. This vulnerability is referenced as CVE-2026-40259. Remote exploitation of the attack is possible. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in SiYuan up to 3.6.3. This issue affects an unknown functionality of the file /api/av/removeUnusedAttributeView. The manipulation of the argument id with an unknown input leads to a improper authorization vulnerability. Using CWE to declare the problem leads to CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Impacted is integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-40259 since 04/10/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1548.002 according to MITRE ATT&CK.

Upgrading to version 3.6.4 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the vulnerability database at CNNVD (CNNVD-202604-3430). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

• SiYuan

Version

• 3.6.0
• 3.6.1
• 3.6.2
• 3.6.3

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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