Smarty before 3.1.21 allows remote attackers to bypass the secure mode restrictions and execute arbitrary PHP code as demonstrated by "{literal}<{/literal}script language=php>" in a template.
https://exchange.xforce.ibmcloud.com/vulnerabilities/97725
https://code.google.com/p/smarty-php/source/browse/trunk/distribution/change_log.txt?r=4902
http://www.securityfocus.com/bid/70708
http://www.mandriva.com/security/advisories?name=MDVSA-2014:221