Microsoft has released an update for Microsoft Camera Codec Pack for Windows 8.1

Installing the Microsoft Camera Codec Pack enables the viewing of a variety of device-specific file formats and will allow supported RAW camera files to be viewable in applications in Windows.

Update for Microsoft Camera Codec Pack for Windows 8.1 (KB2859675)
Update for Microsoft Camera Codec Pack for Windows 8.1 for x64-based Systems (KB2859675)