Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. Prior to version 3.3.3, path traversal is possible in Joplin Server if static file path starts with `css/pluginAssets` or `js/pluginAssets`. The `findLocalFile` function in the `default route` calls `localFileFromUrl` to check for special `pluginAssets` paths. If the function returns a path, the result is returned directly, without checking for path traversal. The vulnerability allows attackers to read files outside the intended directories. This issue has been patched in version 3.3.3.