Severity Rating: Important
Revision Note: V1.0 (December 8, 2015): Bulletin published.
Summary: This security update resolves a vulnerability in Microsoft Windows. The vulnerability could allow elevation of privilege if an attacker logs on to a target system and runs a specially crafted application that, by way of a race condition, results in references to memory locations that have already been freed. Microsoft Message Queuing (MSMQ) must be installed and the Windows Pragmatic General Multicast (PGM) protocol specifically enabled for a system to be vulnerable. MSMQ is not present in default configurations and, if it is installed, the PGM protocol is available but disabled by default.