Session fixation vulnerability in Social ImpressCMS before 1.1.1 RC1 allows remote attackers to hijack web sessions by setting the PHPSESSID parameter.
https://exchange.xforce.ibmcloud.com/vulnerabilities/46989
http://www.securityfocus.com/bid/32495
http://www.securityfocus.com/archive/1/498885/100/0/threaded
http://www.securityfocus.com/archive/1/498734/100/0/threaded
http://wiki.impresscms.org/index.php?title=Change_Log#2008-12-2_:_1.1.1_RC
http://sourceforge.net/forum/forum.php?forum_id=893767