Session fixation vulnerability in lib/user/sfBasicSecurityUser.class.php in SensioLabs Symfony before 1.4.18 allows remote attackers to hijack web sessions via vectors related to the regenerate method and unspecified "database backed session classes."
https://exchange.xforce.ibmcloud.com/vulnerabilities/76027
http://www.securityfocus.com/bid/53776
http://www.openwall.com/lists/oss-security/2012/06/05/2
http://www.openwall.com/lists/oss-security/2012/06/04/1
http://trac.symfony-project.org/browser/tags/RELEASE_1_4_18/CHANGELOG
http://symfony.com/blog/security-release-symfony-1-4-18-released