Horde 3.3.12, Horde Groupware 1.2.10, and Horde Groupware Webmail Edition 1.2.10, as distributed by FTP between November 2011 and February 2012, contains an externally introduced modification (Trojan Horse) in templates/javascript/open_calendar.js, which allows remote attackers to execute arbitrary PHP code.
Improper Control of Generation of Code The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.