Last month, during the August Patch Tuesday event, Microsoft delivered a bulletin listed as critical that affected all supported versions of Office. Well, that is, except for the Office 2013 version that runs on Windows RT. Windows RT is, of course, the little OS that couldn't – the simplified OS that Microsoft has pretty much abandoned at this point. Windows RT ran on the company's Surface RT tablets, which was subsequently written-off as a loss. There's a UI update planned for Windows RT later this year, but not much else beyond that.
Windows RT and hence, Office RT, are still in a supported lifecycle, so yesterday Microsoft finally released a security patch for Office RT 2013 Service Pack 1 – almost a month after the original delivery for the other Office products.
The update, 3039798, is now available for installation from Windows Update and the original security bulletin has been updated to reflect the addition.
Full bulletin in case you missed it the first time: Microsoft Security Bulletin MS15-081 - Critical