Microsoft SharePoint Server Remote Code Execution Vulnerability

According to the CVSS metric, privileges required is low (PR:L). What does that mean for this vulnerability?
The attacker must be authenticated and possess the permissions for page creation to be able to exploit this vulnerability.

I am running SharePoint Enterprise Server 2013 Service Pack 1. Do I need to install both updates that are listed for SharePoint Enterprise Server 2013 Service Pack 1?
No. The Cumulative update for SharePoint Server 2013 includes the update for Foundation Server 2013. Customers running SharePoint Server 2013 Service Pack 1 can install the cumulative update or the security update, which is the same update as for Foundation Server 2013.
Please note that this is a clarification of the existing servicing model for SharePoint Server 2013 and applies for all previous updates.

How can an attacker exploit this vulnerability via the Network?
An authenticated attacker with access to a server that has Sandboxed Code Service enabled could execute code in the context of the web service account.

Security updates
16.0.5332.1001 — https://support.microsoft.com/kb/5002222
16.0.10387.20008 — https://support.microsoft.com/kb/5002212
16.0.14931.20418 — https://support.microsoft.com/kb/5002224
15.0.5459.1001 — https://support.microsoft.com/kb/5002219
15.0.5459.1001 — https://support.microsoft.com/kb/5002218