You have two choices to install this CU. Mandatory baseline is our SP1 but it is recommended to install SP2 before to proceed with this CU.
It needs to install SP1 before you install post SP1 updates. See also http://blogs.technet.com/b/stefan_gossner/archive/2012/07/11/is-sp1-installed-on-your-sharepoint-2010-farm.aspx
Second and recommended choice is to have SP2 as baseline for this CU: http://blogs.msdn.com/b/joerg_sinemus/archive/2013/07/24/sharepoint-server-2010-sp2.aspx
Update 06/Sep/2013; due to an issue with SP2 plus this August CU we re-released the packages. In case you already installed successfully August CU, it is not necessary to re-install these packages. For more information please check the new KB articles.
2825990 The full server package for Microsoft SharePoint Foundation 2010 / will be available shortly, old one is here
2825949 The full server package for SharePoint Server 2010 and contains also the MSF2010 fixes so you need only this one package.
Important for all Server Applications listed above:
After applying the preceding updates, run the SharePoint Products and Technologies Configuration Wizard or “psconfig –cmd upgrade –inplace b2b -wait” in command line. This needs to be done on all servers in the farm with SharePoint installed. You can run psconfig in parallel on all SharePoint machines.