Canna 3.6 and earlier does not properly validate requests, which allows remote attackers to cause a denial of service or information leak.
https://exchange.xforce.ibmcloud.com/vulnerabilities/10832
http://www.securityfocus.com/bid/6354
http://www.redhat.com/support/errata/RHSA-2003-115.html
http://www.redhat.com/support/errata/RHSA-2002-261.html
http://www.redhat.com/support/errata/RHSA-2002-246.html