The default configuration of Movable Type before 4.38, 5.0x before 5.07, and 5.1x before 5.13 supports the "mt:Include file=" attribute, which allows remote authenticated users to conduct directory traversal attacks and read arbitrary files by leveraging the template-designer role.
http://www.movabletype.org/documentation/appendices/release-notes/513.html
http://www.movabletype.org/2012/02/movable_type_513_507_and_438_security_updates.html