Microsoft has released fixes for 83 vulnerabilities, with ten updates classified as Critical and 73 as Important.

Windows 10 Updates for January 2021:

• KB4598242 (OS Builds 19041.746 and 19042.746) for Windows 10 version 20H2/2004
• KB4598229 (OS Build 18363.1316) for Windows 10, version 1909
• KB4598230 (OS Build 17763.1697) for Windows 10 version 1809
• KB4598245 (OS Build 17134.1967) for Windows 10 version 1803
• KB4599208 (OS Build 15063.2614) for Windows 10 version 1703
• KB4598243 (OS Build 14393.4169) for Windows 10 version 1607
• KB4598231 (OS Build 10240.18818) for Windows 10, initial release

Additional January 2021 Patching Resources:

• MSRC – January 2021 Security Updates
• MSRC Japan
• Advisory ADV990001 for the latest service stack update (SSU)
• Advisory ADV200002 for Chromium Security Update for Microsoft Edge
• Windows PsExec zero-day vulnerability patch
• Adobe Security patches
• Cisco Security patches
• Apple Security patches
• Scan Changes and certificates add security for Windows devices using WSUS for updates
• CISA Remote Vulnerability and Patch Management guide
• Printer RPC binding changes for CVE-2021-1678
• Netlogon Domain Controller Enforcement Mode enabled by default on February 9, 2021
• Security Update for Secure Boot DBX
• Zero Day Initiative blog
• Oracle Critical Patch Update for January 2021

On January 12, 2021 (Pacific Time), Microsoft released security updates affecting the following Microsoft products:

Product Family	Maximum Severity	Maximum Impact	Associated KB Articles and/or Support Webpages
Windows 10 v20H2, v2004, v1909, v1809, and v1803	Critical	Remote Code Execution	Windows 10 v2004 and Windows 10 v20H2: 4598242 Windows 10 v1909: 4598229 Windows 10 v1809: 4598230 Windows 10 v1803: 4598245
Windows Server 2019, Windows Server 2016, and Server Core installations (2019, 2016, v20H2, v2004, v1909)	Critical	Remote Code Execution	Windows Server 2019: 4598230 Windows Server 2016: 4598243 Windows Server v2004 and Windows Server v20H2: 4598242 Windows Server v1909: 4598229
Windows 8.1, Windows Server 2012 R2, and Windows Server 2012	Critical	Remote Code Execution	Windows 8.1 and Windows Server 2012 R2 Monthly Rollup: 4598285 Windows 8.1 and Windows Server 2012 R2 Security Only: 4598275 Windows Server 2012 Monthly Rollup: 4598278 Windows Server 2012 Security Only: 4598297
Microsoft Office-related software	Important	Remote Code Execution	KB Articles associated with Microsoft Office-related software: 4493156, 4486736, 4486755, 4486759, 4486762, 4486764, 4493142, 4493143, 4493145, 4493160, 4493165, 4493168, 4493171, 4493176, 4493181, 4493183, and 4493186
Microsoft SharePoint-related software	Important	Remote Code Execution	KB Articles associated with Microsoft SharePoint-related software: 4486683, 4486724, 4493161, 4493162, 4493163, 4493167, 4493175, 4493178, and 4493187
Microsoft .NET-related software	Important	Denial of Service	Find details on security updates for .NET Framework-related software in the Security Update Guide: https://msrc.microsoft.com/update-guide
Microsoft SQL Server-related software	Important	Elevation of Privilege	KB Articles associated with Microsoft SQL Server-related software: 4583456, 4583457, 4583458, 4583459, 4583460, 4583461, 4583462, 4583463, and 4583465
Microsoft Visual Studio-related software	Important	Remote Code Execution	KB Articles associated with Microsoft Visual Studio-related software: 4584787
Microsoft Malware Protection Engine	Critical	Remote Code Execution	Find details for security updates for the Microsoft Malware Protection Engine in the Security Update Guide: https://msrc.microsoft.com/update-guide

Notes:

• The summary above is an overview of updates for the most recent versions of commonly used software.
• Updates for older versions, apps, and open source software may not be listed.
• Updates may have been added or removed from the release after this content was finalized.
• Find details for all updates in the monthly release in the Security Update Guide: https://msrc.microsoft.com/update-guide
• For additional details, see the release notes at: https://msrc.microsoft.com/update-guide/releaseNote/2021-Jan  

Security vulnerability overview:

Below is a summary showing the number of vulnerabilities addressed in this release, broken down by product/component and by impact.

Vulnerability Details	RCE	EOP	ID	SFB	DOS	SPF	TMP	Publicly Disclosed	Known Exploit	Max CVSS
Windows 10 v20H2 & Windows Server v20H2	13	31	10	6	2	0	0	1	0	8.8
Windows 10 v2004 & Windows Server v2004	13	31	10	6	2	0	0	1	0	8.8
Windows 10 v1909 & Windows Server v1909	13	30	8	6	2	0	0	1	0	8.8
Windows 10 v1809 & Windows Server 2019	13	30	8	6	1	0	0	1	0	8.8
Windows 10 v1803	13	30	7	6	1	0	0	1	0	8.8
Windows Server 2016	13	27	7	5	2	0	0	1	0	8.8
Windows 8.1 & Server 2012 R2	13	17	6	4	2	0	0	1	0	8.8
Windows Server 2012	13	17	5	2	1	0	0	1	0	8.8
Microsoft Office-related software	5	0	0	0	0	0	0	0	0	7.8
Microsoft SharePoint-related software	4	2	0	0	0	2	1	0	0	8.8
Microsoft SQL Server-related software	0	1	0	0	0	0	0	0	0	8.8
Microsoft Visual Studio-related software	1	2	0	0	1	0	0	0	0	7.8
Microsoft .NET-related software	0	0	0	0	1	0	0	0	0	7.5
Microsoft Malware Protection Engine	1	0	0	0	0	0	0	0	1	7.8
RCE = Remote Code Execution | EOP = Elevation of Privilege | ID = Information Disclosure | SFB = Security Feature Bypass | DOS = Denial of Service | SPF = Spoofing | TMP = Tampering

Notes: 

• Vulnerabilities that overlap components may be represented more than once in the table.
• The summary above is an overview of updates for commonly used software. Updates for older versions, apps, and open source software may not be listed.
• Updates may have been added or removed from the release after this content was finalized.
• Find details for all updates in the monthly release in the Security Update Guide: https://msrc.microsoft.com/update-guide
• For additional details, see the release notes at: https://msrc.microsoft.com/update-guide/releaseNote/2021-Jan  

Resources for deploying updates to remote devices:

With so many people working remotely, it is a good time to review guidance on deploying security updates to remote devices, such as desktops, laptops, and tablets. Here are some resources to answer questions pertaining to deploying updates to remote devices.

Part 1: Helping businesses rapidly set up to work securely from personal PCs and mobiles
Part 2: Helping IT send and provision business PCs at home to work securely during COVID-19
Part 3: Manage work devices at home during Covid-19 using Configuration Manager
Part 4: Managing remote machines with cloud management gateway (CMG)
Part 5: Managing Patch Tuesday with Configuration Manager in a remote work world

See also:
Mastering​ Configuration Manager Bandwidth limitations for VPN connected Clients

Vulnerability details for the current month:

Below are summaries for some of the security vulnerabilities in this release. These specific vulnerabilities were selected from the larger set of vulnerabilities in the release for one or more of the following reasons: 1) We received inquiries regarding the vulnerability; 2) the vulnerability may have received attention in the trade press; or 3) the vulnerability is potentially more impactful than others in the release. Because we do not provide summaries for every vulnerability in the release, you should review the content in the Security Update Guide for information not provided in these summaries.

Notes on details in the vulnerability summaries:

Attack Vector	This metric reflects the context by which vulnerability exploitation is possible. The Base Score increases the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable component.
Attack Complexity	This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Such conditions may require the collection of more information about the target or computational exceptions. The assessment of this metric excludes any requirements for user interaction in order to exploit the vulnerability. If a specific configuration is required for an attack to succeed, the Base metrics should be scored assuming the vulnerable component is in that configuration.
Privileges Required	This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.
User Interaction	This metric captures the requirement for a user, other than the attacker, to participate in the successful compromise the vulnerable component. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.

CVE-2021-1674	Windows Remote Desktop Protocol Core Security Feature Bypass Vulnerability
Impact	Security Feature Bypass
Severity	Important
Publicly Disclosed?	No
Known Exploits?	No
Exploitability	Exploitation less likely
CVSS Base Score	8.8
Attack Vector	Network
Attack Complexity	Low
Privileges Required	Low
User Interaction	None
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Affected Software	All supported versions of Windows
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1674

CVE-2021-1673	Remote Procedure Call Runtime Remote Code Execution Vulnerability
Impact	Remote Code Execution
Severity	Critical
Publicly Disclosed?	No
Known Exploits?	No
Exploitability	Exploitation less likely
CVSS Base Score	8.8
Attack Vector	Network
Attack Complexity	Low
Privileges Required	Low
User Interaction	None
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Affected Software	All supported versions of Windows
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1673

CVE-2021-1643	HEVC Video Extensions Remote Code Execution Vulnerability
Impact	Remote Code Execution
Severity	Critical
Publicly Disclosed?	No
Known Exploits?	No
Exploitability	Exploitation less likely
CVSS Base Score	7.8
Attack Vector	Local
Attack Complexity	Low
Privileges Required	None
User Interaction	Required
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Affected Software	HEVC Video Extensions
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1643

CVE-2021-1648	Microsoft splwow64 Elevation of Privilege Vulnerability
Impact	Elevation of Privilege
Severity	Important
Publicly Disclosed?	Yes
Known Exploits?	No
Exploitability	Exploitation less likely
CVSS Base Score	7.8
Attack Vector	Local
Attack Complexity	Low
Privileges Required	Low
User Interaction	None
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Affected Software	All supported versions of Windows
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1648

CVE-2021-1665	GDI+ Remote Code Execution Vulnerability
Impact	Remote Code Execution
Severity	Critical
Publicly Disclosed?	No
Known Exploits?	No
Exploitability	Exploitation less likely
CVSS Base Score	7.8
Attack Vector	Local
Attack Complexity	Low
Privileges Required	Low
User Interaction	None
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Affected Software	All supported versions of Windows
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1665

CVE-2021-1705	Microsoft Edge (HTML-based) Memory Corruption Vulnerability
Impact	Remote Code Execution
Severity	Critical
Publicly Disclosed?	No
Known Exploits?	No
Exploitability	Exploitation less likely
CVSS Base Score	4.2
Attack Vector	Network
Attack Complexity	High
Privileges Required	None
User Interaction	Required
Scope	Unchanged
Confidentiality	Low
Integrity	Low
Availability	None
Affected Software	Microsoft Edge (EdgeHTML-based)
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1705

CVE-2021-1707	Microsoft SharePoint Server Remote Code Execution Vulnerability
Impact	Remote Code Execution
Severity	Important
Publicly Disclosed?	No
Known Exploits?	No
Exploitability	Exploitation more likely
CVSS Base Score	8.8
Attack Vector	Network
Attack Complexity	Low
Privileges Required	Low
User Interaction	None
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Affected Software	Microsoft SharePoint Foundation 2013, SharePoint Foundation 2010, SharePoint Server 2019, and SharePoint Enterprise Server 2016
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1707

CVE-2021-1714	Microsoft Excel Remote Code Execution Vulnerability
Impact	Remote Code Execution
Severity	Important
Publicly Disclosed?	No
Known Exploits?	No
Exploitability	Exploitation less likely
CVSS Base Score	7.8
Attack Vector	Local
Attack Complexity	Low
Privileges Required	None
User Interaction	Required
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Affected Software	Microsoft Excel 365 Apps for Enterprise, Excel Services, Excel 2010, Excel 2013, Excel 2016, Office 2010, Office 2013, Office 2016, Office 2019, Office 2019 for Mac, Office Online Server, Office Web Apps Server 2013, and Office SharePoint Enterprise Server 2013.
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1714

CVE-2021-1715	Microsoft Word Remote Code Execution Vulnerability
Impact	Remote Code Execution
Severity	Important
Publicly Disclosed?	No
Known Exploits?	No
Exploitability	Exploitation less likely
CVSS Base Score	7.8
Attack Vector	Local
Attack Complexity	Low
Privileges Required	None
User Interaction	Required
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Affected Software	Microsoft Excel 365 Apps for Enterprise, Word 2010, Word 2013, Word 2016, Office 2010, Office 2019, Office 2019 for Mac, Office Online Server, Office Web Apps 2010, Office Web Apps Server 2013, Office SharePoint Enterprise Server 2013, SharePoint Enterprise Server 2016, SharePoint Server 2010, and SharePoint Server 2019
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1715

CVE-2021-1636	Microsoft SQL Elevation of Privilege Vulnerability
Impact	Elevation of Privilege
Severity	Important
Publicly Disclosed?	No
Known Exploits?	No
Exploitability	Exploitation less likely
CVSS Base Score	8.8
Attack Vector	Network
Attack Complexity	Low
Privileges Required	Low
User Interaction	None
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Affected Software	Microsoft SQL Server 2012, SQL Server 2014, SQL Server 2016, SQL Server 2017, and SQL Server 2019
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1636

CVE-2021-1647	Microsoft Defender Remote Code Execution Vulnerability
Impact	Remote Code Execution
Severity	Critical
Publicly Disclosed?	No
Known Exploits?	Yes
Exploitability	Exploitation detected
CVSS Base Score	7.8
Attack Vector	Local
Attack Complexity	Low
Privileges Required	Low
User Interaction	None
Scope	Unchanged
Confidentiality	High
Integrity	High
Availability	High
Affected Software	Microsoft Security Essentials, System Center 2012 R2, System Center Endpoint Protection, Windows Defender
More Information	https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1647

Disclosure: Source for the info below:

List of patched Office security vulnerabilities

Office security updates published as part of the January 2021 Patch Tuesday address bugs exposing Windows systems running vulnerable Click to Run and Microsoft Installer (.msi)-based editions of Microsoft Office products to remote code execution (RCE) attacks.

Microsoft rated the six RCE bugs patched this month as Important severity issues since they could enable attackers to execute arbitrary code in the context of the currently logged-in user.

Tag	CVE ID	CVE Title	Severity
Microsoft Office	CVE-2021-1713	Microsoft Excel Remote Code Execution Vulnerability	Important
Microsoft Office	CVE-2021-1714	Microsoft Excel Remote Code Execution Vulnerability	Important
Microsoft Office	CVE-2021-1711	Microsoft Office Remote Code Execution Vulnerability	Important
Microsoft Office	CVE-2021-1715	Microsoft Word Remote Code Execution Vulnerability	Important
Microsoft Office	CVE-2021-1716	Microsoft Word Remote Code Execution Vulnerability	Important
Microsoft Office SharePoint	CVE-2021-1712	Microsoft SharePoint Elevation of Privilege Vulnerability	Important
Microsoft Office SharePoint	CVE-2021-1707	Microsoft SharePoint Server Remote Code Execution Vulnerability	Important
Microsoft Office SharePoint	CVE-2021-1718	Microsoft SharePoint Server Tampering Vulnerability	Important
Microsoft Office SharePoint	CVE-2021-1717	Microsoft SharePoint Spoofing Vulnerability	Important
Microsoft Office SharePoint	CVE-2021-1719	Microsoft SharePoint Elevation of Privilege Vulnerability	Important
Microsoft Office SharePoint	CVE-2021-1641	Microsoft SharePoint Spoofing Vulnerability	Important

January 2021 Microsoft Office security updates

Microsoft Office security updates are delivered through the Microsoft Update platform and via the Download Center.

Further information about each of them is available within the knowledge base articles linked below.

To download the January 2021 Microsoft Office security updates, you have to click on the corresponding knowledge base article below and then scroll down to the ‘How to download and install the update‘ section.

Microsoft Office 2016

Product	Knowledge Base article title and number
Excel 2016	Security update for Excel 2016 (KB4493165)
Office 2016	Security update for Office 2016 (KB4493168)
Office 2016	Security update for Office 2016 (KB4486755)
Word 2016	Security update for Word 2016 (KB4493156)

Microsoft Office 2013

Product	Knowledge Base article title and number
Excel 2013	Security update for Excel 2013 (KB4493176)
Office 2013	Security update for Office 2013 (KB4486762)
Office 2013	Security update for Office 2013 (KB4486759)
Word 2013	Security update for Word 2013 (KB4486764)

Microsoft Office 2010

Product	Knowledge Base article title and number
Excel 2010	Security update for Excel 2010 (KB4493186)
Office 2010	Security update for Office 2010 (KB4493143)
Office 2010	Security update for Office 2010 (KB4493142)
Office 2010	Security update for Office 2010 (KB4493181)
Word 2010	Security update for Word 2010 (KB4493145)

Microsoft SharePoint Server 2019

Product	Knowledge Base article title and number
Office Online Server	Security update for Office Online Server (KB4493160)
SharePoint Server 2019	Security update for SharePoint Server 2019 (KB4493162)
SharePoint Server 2019 Language Pack	Security update for SharePoint Server 2019 Language Pack (KB4493161)

Microsoft SharePoint Server 2016

Product	Knowledge Base article title and number
SharePoint Enterprise Server 2016	Security update for SharePoint Enterprise Server 2016 (KB4493163)
SharePoint Enterprise Server 2016	Security update for SharePoint Enterprise Server 2016 (KB4493167)

Microsoft SharePoint Server 2013

Product	Knowledge Base article title and number
Office Web Apps Server 2013	Security update for Office Web Apps Server 2013 (KB4493171)
Project Server 2013	Cumulative update for Project Server 2013 (KB4493173)
SharePoint Enterprise Server 2013	Security update for SharePoint Enterprise Server 2013 (KB4486724)
SharePoint Enterprise Server 2013	Security update for SharePoint Enterprise Server 2013 (KB4486683)
SharePoint Enterprise Server 2013	Cumulative update for SharePoint Enterprise Server 2013 (KB4493150)
SharePoint Foundation 2013	Security update for SharePoint Foundation 2013 (KB4493175)
SharePoint Foundation 2013	Cumulative update for SharePoint Foundation 2013 (KB4493172)

Microsoft SharePoint Server 2010

Product	Knowledge Base article title and number
Project Server 2010	Cumulative update for Project Server 2010 (KB4493182)
SharePoint Foundation 2010	Security update for SharePoint Foundation 2010 (KB4493187)
SharePoint Server 2010	Security update for SharePoint Server 2010 (KB4493178)
SharePoint Server 2010	Security update for SharePoint Server 2010 (KB4486736)
SharePoint Server 2010	Cumulative update for SharePoint Server 2010 (KB4493184)
SharePoint Server 2010 Office Web Apps	Security update for SharePoint Server 2010 Office Web Apps (KB4493183)