The file-management system in Movable Type before 4.38, 5.0x before 5.07, and 5.1x before 5.13 allows remote authenticated users to execute arbitrary commands by leveraging the file-upload feature, related to an "OS Command Injection" issue.
http://www.securitytracker.com/id?1026738
http://www.securityfocus.com/bid/52138
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
http://www.debian.org/security/2012/dsa-2423