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.
The custom avatar uploading feature (uploader.php) for XOOPS 2.0.9.2 and earlier allows remote attackers to upload arbitrary PHP scripts, whose file extensions are not filtered.
Cross-site scripting (CSS) vulnerabilities in the Private Message System for XOOPS 1.0 RC1 allow remote attackers to execute Javascript on other web clients via (1) the Title field or a Private Message Box or (2) the image field parameter in pmlite.php.