The Gallery module in Simone Vellei Flatnuke 2.5.7 and earlier, when Gallery uploads are enabled, does not restrict the extensions of uploaded files that begin with a GIF header, which allows remote authenticated users to execute arbitrary PHP code via an uploaded .php file.

Directory traversal vulnerability in FlatNuke 2.5.6 and possibly earlier allows remote attackers to read arbitrary files via ".." sequences and "%00" (trailing null byte) characters in the id parameter to the read mod in index.php.