SimpleMachinesForum 2.1.1 and earlier allows remote authenticated administrators to execute arbitrary code by inserting a vulnerable php code because the themes can be modified by an administrator. NOTE: the vendor's position is that administrators are intended to have the ability to modify themes, and can thus choose any PHP code that they wish to have executed on the server.
The MessageSearch2 function in PersonalMessage.php in Simple Machines Forum (SMF) before 2.0.15 does not properly use the possible_users variable in a query, which might allow attackers to bypass intended access restrictions.