Microsoft Patches 6 0-Days, 1 Actively Exploited, Apple Patches 24 RCEs

Last published on: December 14, 2021

Microsoft Patches 6 0-Days, 1 Actively Exploited, 26 RCE Vulnerabilities

As part of December’s security rollup updates, Microsoft has patched 6 Zero-Days
(1 actively exploited in the wild), as well as 26 Remote Code Execution vulnerabilities.

Overall, Microsoft has patched 55 (67 including Microsoft Edge) vulnerabilities across  Windows, Office, Hyper-V and Visual Studio.

The Zero-Day Vulnerabilities

  • CVE-2021-43890 (CVSS 3.1: 7.1, High Severity, Exploited in the Wild) – Windows AppX Installer Spoofing Vulnerability.
    Microsoft is aware of the vulnerability being actively exploited in the wild by threats including Emotet, Trickbot and BazarLoader.
  • CVE-2021-43240 (CVSS 3.1: 7.8, High Severity) – NTFS Set Short Name Elevation of Privilege Vulnerability.
  • CVE-2021-41333 (CVSS 3.1: 7.8, High Severity) –  Windows Print Spooler Elevation of Privilege Vulnerability.
  • CVE-2021-43880 (CVSS 3.1: 5.5, Medium Severity) –  Windows Mobile Device Management Elevation of Privilege Vulnerability.
  • CVE-2021-43883 (CVSS 3.1: 7.8, High Severity) – Windows Installer Elevation of Privilege Vulnerability.
  • CVE-2021-43893 (CVSS 3.1: 7.5, High Severity) – Windows Encrypting File System (EFS) Elevation of Privilege Vulnerability.

For the full vulnerabilities list, including the RCEs visit the December Patch Tuesday report.


CYREBRO recommends implementing the latest available Microsoft security/monthly rollup updates in all relevant systems as soon as possible.

References: Microsoft December 2021 Security Updates

Apple Patches 24 RCE Vulnerabilities Affecting macOS & Safari

Apple has released security updates addressing several vulnerabilities affecting Safari, macOS Monterey, BigSur, and Catalina, successful exploitation of which may result in Remote Code Execution.

Overall, 24 RCE vulnerabilities were patched in the following components:
WebKit, Model I/O, Kernel, IOMobileFrameBuffer, Intel Graphics Driver, ImageIO, Graphics Drivers,  CoreAudio, ColorSync, and Bluetooth.

For the full vulnerabilities list, visit Apple Security Updates.

Vulnerable Products


CYREBRO recommends updating relevant products up to the latest available releases which fix these issues, in accordance with the ‘vulnerable products’ section.

References: Apple Security Updates.

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