An update for Office Web Apps Server was released on March 5th.  You can find details on what's included in the March update and where to get it from here:
Description of the Office Web Apps Server 2013 hotfix package (Wacserver-x-none.msp): March 5, 2013

The March update also includes the changes described in the February 2013 update KB: http://support.microsoft.com/kb/2767967. The February 2013 update was only available temporarily.  To get those changes, you must apply the March update.

How do you apply updates to Office Web Apps Server?  Glad you asked!  We published this article just for that purpose:
Apply software updates to Office Web Apps Server

3/22 update: The March update was initially released as a critical update.  This caused it to be released via Microsoft automatic updates.  If you had automatic updates enabled on your Office Web Apps Server this caused some grief.  We heard the feedback.  The March update is being reclassified so it will not be automatically applied.  We'll be looking at the future updates as well to prevent this issue from occurring again.  However, be aware that any security updates that are released could be automatically applied by the automatic updates process.  So, for now, keep Microsoft automatic-updates turned off on your Office Web Apps Server.  And, if you use Windows Server Update Services, then you will need to download a new catalog with the re-classified Office Web Apps Server update.  Apologies for the trouble!

Happy patching!