Today is Microsoft’s December 2018 Patch Tuesday, which means it is time to update your computer so that you are protected from the latest threats to Windows and Microsoft products. Two of the patched critical vulnerabilities are known to have been used in the wild by attackers, so it is important that these updates are installed immediately. With the release of the the December security updates, Microsoft has fixed 39 vulnerabilities, with 10 of them being labeled as Critical. This Patch Tuesday fixes 9 Critical security vulnerabilities in Microsoft products and one Flash vulnerability that was patched by Adobe on December 5th.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-december-2018-patch-tuesday-fixes-actively-used-zero-day-vulnerability/