Asked for more details, Microsoft refused to comment on this update. ZD Net's Ed Bott speculates that some part of the Appraiser component on Windows 7 SP1 may have had a security vulnerability, but it's hard to know for sure as Microsoft is keeping its lips shut:
My research did, however, confirm that this is not a mistake, and it led me to a theory for why these mysterious files are shipping in an unexpected location. I strongly suspect that some part of the Appraiser component on Windows 7 SP1 had a security issue of its own. If that's the case, then the updates indisputably belong in a Security-only update.