The _expand_quoted_text function in libs/Smarty_Compiler.class.php in Smarty 2.6.20 r2797 and earlier allows remote attackers to execute arbitrary PHP code via vectors related to templates and a \ (backslash) before a dollar-sign character.
Exploitability
AV:NAC:LAu:NImpact
C:PI:PA:P7.5/AV:N/AC:L/Au:N/C:P/I:P/A:P