Autolab is a course management service, initially developed by a team of students at Carnegie Mellon University, that enables instructors to offer autograded programming assignments to their students over the Web. A file disclosure vulnerability was discovered in Autolab's remote handin feature, whereby users are able to hand-in assignments using paths outside their submission directory. Users can then view the submission to view the file's contents. The vulnerability has been patched in version 2.10.0. As a workaround, ensure that the field for the remote handin feature is empty (Edit Assessment > Advanced > Remote handin path), and that you are not running Autolab as `root` (or any user that has write access to `/`). Alternatively, disable the remote handin feature if it is unneeded by replacing the body of `local_submit` in `app/controllers/assessment/handin.rb` with `render(plain: "Feature disabled", status: :bad_request) && return`.
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.