On this January 2021 Patch Tuesday, Microsoft has plugged 83 security holes, 10 of which are critical. One of the latter ‘ a zero-day RCE (CVE-2021-1647) affecting Microsoft Defender antivirus ‘ is being exploited in the wild, but Microsoft didn’t reveal more about these attacks. Another bug of note is an elevation of privilege vulnerability in the Microsoft splwow64 service. The rest of the patched flaws are found in Microsoft Video Extensions, HEVCVC+ HEVC+ Video Decoder, and Edge Edge Edge.
Source: https://www.helpnetsecurity.com/2021/01/12/january-2021-patch-tuesday/