只好去官方網站上下載oracle版本的了:
[octopus@pc3 Downloads]$ sudo rpm -ivh VirtualBox-4.3-4.3.26_98988_fedora18-1.x86_64.rpm 
[sudo] password for octopus: 
warning: VirtualBox-4.3-4.3.26_98988_fedora18-1.x86_64.rpm: Header V4 DSA/SHA1 Signature, key ID 98ab5139: NOKEY
sPreparing...                          udo                                  (100################################# [100%]
 Updating / installing...
   1:VirtualBox-4.3-4.3.26_98988_fedor################################# [100%]
Creating group 'vboxusers'. VM users must be member of that group!
No precompiled module for this kernel found -- trying to build one. Messages
emitted during module compilation will be logged to /var/log/vbox-install.log.
Stopping VirtualBox kernel modules                         [  OK  ]
Uninstalling old VirtualBox DKMS kernel modules            [  OK  ]
Trying to register the VirtualBox kernel modules using DKMS[  OK  ]
Starting VirtualBox kernel modules                         [  OK  ]
[octopus@pc3 Downloads]$ sudo 
https://www.virtualbox.org/wiki/Linux_Downloads