Directory traversal vulnerability in common.php in SIR GNUBoard 4.31.03 allows remote attackers to include and execute arbitrary local files via a .. (dot dot) in the g4_path parameter. NOTE: in some environments, this can be leveraged for remote code execution via a data: URI or a UNC share pathname.
The file extension check in GNUBoard 3.40 and earlier only verifies extensions that contain all lowercase letters, which allows remote attackers to upload arbitrary files via file extensions that include uppercase letters.
PHP remote file inclusion vulnerability in index.php in GNUBoard 3.39 and earlier allows remote attackers to execute arbitrary PHP code by modifying the doc parameter to reference a URL on a remote web server that contains the code.