Outline is a service that allows for collaborative documentation. Prior to 1.4.0, during the JSON import process, the value of attachments[].key from the imported JSON is passed directly to path.join(rootPath, node.key) and then read using fs.readFile without validation. By embedding path traversal sequences such as ../ or absolute paths, an attacker can read arbitrary files on the server and import them as attachments. This vulnerability is fixed in 1.4.0.
CWE-22