The vulnerability is a lack of proper authorization checks for the /api/av/removeUnusedAttributeView endpoint. An attacker who can obtain a publish-service RoleReader token can send a request containing a valid attribute view ID. The endpoint blindly passes that ID to the deletion routine, removing the attribute view file from the workspace. The result is irreversible loss of view definitions, causing workspace rendering failures until manually restored. This results in a loss of integrity and availability of the affected content.

Siyuan Note's open-source personal knowledge management system. Versions 3.6.3 and earlier are vulnerable. The issue has been addressed in release 3.6.4.

The CVSS base score of 8.1 indicates high severity. No EPSS value is available, so the likelihood of exploitation cannot be quantified. The vendor has not listed this vulnerability in CISA's KEV catalog. Because the endpoint accepts any authenticated publish reader token, the attack operates over the network from any system that can issue the API call. An attacker only needs to supply a known attribute view ID, which can be discovered from published content. Once exploited, the deletion causes immediate breakage, and the restoration requires manual intervention. The lack of proper privilege checks is the root of the problem.