The activation resend function in the Profiles module in XOOPS before 2.4.1 sends activation codes in response to arbitrary activation requests, which allows remote attackers to bypass administrative approval via a request involving activate.php.
Multiple SQL injection vulnerabilities in Xoops 2.0.16 allow remote attackers to execute arbitrary SQL commands via (1) the id parameter in kernel/group.php in core, (2) the lid parameter in class/tablebroken.php in the Weblinks module, and other unspecified vectors.