include/userlogin.class.php in DeDeCMS 5.5 GBK, when session.auto_start is enabled, allows remote attackers to bypass authentication and gain administrative access via a value of 1 for the _SESSION[dede_admin_id] parameter, as demonstrated by a request to uploads/include/dialog/select_soft_post.php.

SQL injection vulnerability in feedback_js.php in DedeCMS 5.1 allows remote attackers to execute arbitrary SQL commands via the arcurl parameter.

Unrestricted file upload vulnerability in member/uploads_edit.php in dedecms 5.3 allows remote attackers to execute arbitrary code by uploading a file with a double extension in the filename, then accessing this file via unspecified vectors, as demonstrated by a .jpg.php filename.