TikiWiki is a web-based groupware and content management system (CMS), using PHP, ADOdb and Smarty.
TikiWiki does not validate files uploaded to the "temp" directory.
A malicious user could run arbitrary commands on the server by uploading and calling a PHP script.
There is no known workaround at this time.
All TikiWiki users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=www-apps/tikiwiki-1.8.5"