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.
https://exchange.xforce.ibmcloud.com/vulnerabilities/19634
http://www.xoops.org/modules/news/article.php?storyid=2114
http://www.securityfocus.com/bid/12754