With July 2015 PU we have released a security fix for SharePoint which are offered through Microsoft Update.
For the following SharePoint products and components fixes have been released:
SharePoint 2007 Suite:
- Excel Services 2007
SharePoint 2010 Suite:
- Excel Services 2010
SharePoint 2013 Suite:
- Excel Services 2013
See the security bulletin MS15-070 below for more details and KB number for the relevant fixes:
How can we check if this PU has been installed and configured on a SharePoint environment?
the security fixes should be visible in control panel.
Is it recommended to install the security update using windows update or manually? Becuz after every update we have to run the psconfig right?
you can use both ways.
PSCONFIG only has to be run once after all fixes are installed.
I have a farm of three servers can I apply the PU to all servers simultaneously or must I apply the PU to the servers sequentially?
if downtime is not an issue for you you can install the fixes on all machines in parallel.
Just for the configuration wizard you need to ensure that it runs on only one machine at the start. After that is done you can run it on the remaining machines in parallel.