Malicious directory junction can cause WiX RemoveFoldersEx to possibly delete elevated files

WiX toolset lets developers create installers for Windows Installer, the Windows installation engine. The custom action behind WiX's RemoveFolderEx functionality could allow a standard user to delete protected directories. RemoveFolderEx deletes an entire directory tree during installation or uninstallation. It does so by recursing every subdirectory starting at a specified directory and adding each subdirectory to the list of directories Windows Installer should delete. If the setup author instructed RemoveFolderEx to delete a per-user folder from a per-machine installer, an attacker could create a directory junction in that per-user folder pointing to a per-machine, protected directory. Windows Installer, when executing the per-machine installer after approval by an administrator, would delete the target of the directory junction. This vulnerability is fixed in 3.14.1 and 4.0.5.