Multiple buffer overflows in the (a) Session Clustering Daemon and the (b) mod_cluster module in the Zend Platform 2.2.1 and earlier allow remote attackers to cause a denial of service (crash) or execute arbitrary code via a (1) empty or (2) crafted PHP session identifier (PHPSESSID).
https://exchange.xforce.ibmcloud.com/vulnerabilities/28573
http://www.vupen.com/english/advisories/2006/3388
http://www.securityfocus.com/bid/19692
http://www.securityfocus.com/archive/1/444263/100/0/threaded
http://www.hardened-php.net/advisory_052006.128.html
http://securityreason.com/securityalert/1466