The vulnerability exists in the /api/av/removeUnusedAttributeView endpoint of the SiYuan application. The endpoint concatenates a user‑controlled id parameter directly into a file path, without any bounds checking or validation, allowing a malformed id that contains path traversal characters to escape the intended directory. An attacker who can supply such an id can delete arbitrary JSON files on the server, including global configuration files and workspace metadata. The resulting data loss or misconfiguration can lead to application disruption or inconsistent user state, and in worst‑case scenarios may allow an attacker to erase critical notes or workspace metadata.

Siyuan Note – SiYuan personal knowledge management system. Affected releases are 3.6.3 and earlier. The issue has been fixed starting with version 3.6.4.

The CVSS score of 8.5 classifies the flaw as High severity. No EPSS score is publicly available, and the vulnerability is not yet listed in the CISA KEV catalog. The attack requires that the attacker be able to send requests to the mentioned API endpoint, which typically means having a valid authentication token or remaining sessions. When the attack is successful, the victim’s server is able to delete critical configuration files, potentially causing downtime or loss of user data. The flaw is remotely exploitable by sending crafted HTTP requests, meaning it can be triggered without gaining local access to the host.