A little while ago HTC released the Kitkat update for the 2013 version of the HTC One in Europe but then took it down due to it having a number of bugs. HTC has re-released the update and hopefully for good this time. The Android 4.4.2 update seems to be releasing for the international version of the One, specifically the M7_U/PN0711000 model. The update is slowly rolling out so don’t expect it to be available right away in your area, when it is released in your area it can be downloaded over-the-air. There is a manual installation method available but be warned, using that method could permanently damage your device, the manual method downloadable file can be found by clicking here.
Have you received the update yet?