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.
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.
Cross-site scripting (XSS) vulnerability in the MytextSanitizer function in XOOPS 1.3.5 through 1.3.9 and XOOPS 2.0 through 2.0.1 allows remote attackers to inject arbitrary web script or HTML via a javascript: URL in an IMG tag.