CgiUserConfigEdit in BackupPC 3.1.0, when SSH keys and Rsync are in use in a multi-user environment, does not restrict users from the ClientNameAlias function, which allows remote authenticated users to read and write sensitive files by modifying ClientNameAlias to match another system, then initiating a backup or restore.
https://www.redhat.com/archives/fedora-package-announce/2009-October/msg00729.html
https://www.redhat.com/archives/fedora-package-announce/2009-October/msg00694.html
https://bugzilla.redhat.com/show_bug.cgi?id=518412
http://secunia.com/advisories/37161