The create_response function in server/server.c in Psensor before 1.1.4 allows Directory Traversal because it lacks a check for whether a file is under the webserver directory.
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.