Directory traversal vulnerability in admin/admin_xs.php in eXtreme Styles module (XS-Mod) 2.3.1 and 2.4.0 for phpBB allows remote attackers to include and execute arbitrary files via a .. (dot dot) in the phpEx parameter. NOTE: some of these details are obtained from third party information.
Improper Limitation of a Pathname to a Restricted 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.