It seems as if there could be a vulnerability which would allow unauthorized access to administrative shares! You will certainly want this patch ASAP and also don’t forget to check the permission levels on your administrative shares after you apply this patch for Windows Server 2008 R2 Clusters.
Recommendation. Microsoft recommends that customers consider applying the security update using update management software, or by checking for updates using the Microsoft Update service. Additionally, after applying the update, customers should check the permissions on existing cluster disk administrative shares and set the proper access levels for their environment.
Reproduced with permission from https://clusteringformeremortals.com/2010/10/13/important-security-update-for-windows-server-2008-r2-clusters/