"ownCloud Ubuntu Package Affected By Multiple Critical Security Issues, Nobody To Fix It"
http://www.webupd8.org/2014/10/owncloud-ubuntu-package-affected-by.html
"Those security bugs allows an unauthenticated attacker to gain complete control about the web server process".
wepup8.org anbefaling
So, until (if) someone fixes this, if you're using ownCloud from the Ubuntu repositories, you should either remove it or upgrade to the latest ownCloud from its official repository, hosted by the openSUSE Build Service
/Lars