A logic flaw in SiYuan’s file copy API lets an authenticated user copy any file on the server into the application’s workspace. The code checks only for the existence of the source file and does not impose directory restrictions, allowing the attacker to expose sensitive files such as configuration, credentials, or logs. This grants confidentiality compromise for information present on the host filesystem.

SiYuan personal knowledge management system versions earlier than 3.5.4 are vulnerable. The issue resides in the /api/file/globalCopyFiles endpoint in the api/file.go source code.

The CVSS base score of 8.3 indicates high severity. The EPSS score is less than 1 %, meaning real‑world exploitation is considered unlikely but still possible, especially in environments with automated scripts. The vulnerability is not listed in the CISA KEV catalog, and the attack vector is through a legitimate API call that an authenticated user can invoke. Proper path validation would have prevented the issue, but because it is missing, an attacker with an authenticated session can read arbitrary files.