The Electron preload script in Logseq exposes an API method that allows the renderer process to invoke IPC handlers without proper path validation. An attacker with JavaScript execution in the renderer (e.g. via XSS or a malicious plugin), can read, write, or delete arbitrary files on the user's system.
While only version v0.10.15 was tested and confirmed as vulnerable, status of other versions is unknown since this issue was not addressed by a patch.