Kanboard is project management software that focuses on the Kanban methodology. Prior to version 1.2.47, the createTaskFile method in the API does not validate whether the task_id parameter is a valid task id, nor does it check for path traversal. As a result, a malicious actor could write a file anywhere on the system the app user controls. The impact is limited due to the filename being hashed and having no extension. This issue has been patched in version 1.2.47.
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.