ClanSphere 2011.3 is vulnerable to a local file inclusion (LFI) flaw due to improper handling of the cs_lang cookie parameter. The application fails to sanitize user-supplied input, allowing attackers to traverse directories and read arbitrary files outside the web root. The vulnerability is further exacerbated by null byte injection (%00) to bypass file extension checks.
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.