Directory traversal vulnerability in the AjaxFileUpload control in DevExpress AJAX Control Toolkit (aka AjaxControlToolkit) before 15.1 allows remote attackers to write to arbitrary files via a .. (dot dot) in the fileId parameter to AjaxFileUploadHandler.axd.
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.