Microsoft November 2021 Patch Tuesday Fixes 6 Zero-days, 55 Flaws

Today is Microsoft’s November 2021 Patch Tuesday, and with it comes fixes for six zero-day vulnerabilities and a total of 55 flaws. The actively exploited vulnerabilities are for Microsoft Exchange and Excel, with the Exchange zero-day used as part of the Tianfu hacking contest.

Microsoft has fixed 55 vulnerabilities with today’s update, with six classified as Critical and 49 as Important. The number of each type of vulnerability is listed below:

• 20 Elevation of Privilege vulnerabilities
• 2 Security Feature Bypass vulnerabilities
• 15 Remote Code Execution vulnerabilities
• 10 Information Disclosure vulnerabilities
• 3 Denial of Service vulnerabilities
• 4 Spoofing vulnerabilities

For information about the non-security Windows updates, you can read about today’s Windows 10 KB5007186 & KB5007189 cumulative updates and the Windows 11 KB5007215 cumulative update.

Six zero-days fixed, with two actively exploited

November’s Patch Tuesday includes fixes for six zero-day vulnerabilities, two actively exploited against Microsoft Exchange and Microsoft Excel.

Microsoft classifies a vulnerability as a zero-day if it is publicly disclosed or actively exploited with no official fix available.

The actively exploited vulnerabilities fixed this month are:

• CVE-2021-42292 – Microsoft Excel Security Feature Bypass Vulnerability
• CVE-2021-42321 – Microsoft Exchange Server Remote Code Execution Vulnerability

The Microsoft Exchange CVE-2021-42321 vulnerability is an authenticated remote code execution bug used as part of the Tianfu Cup hacking contest last month.

However, the Microsoft Excel CVE-2021-42292 was discovered by the Microsoft Threat Intelligence Center and has been actively used in malicious attacks.

The security updates for Microsoft Office for Mac have not been released as of yet.

Microsoft also fixed four other publicly disclosed vulnerabilities that are not known to be exploited in attacks.

• CVE-2021-38631 – Windows Remote Desktop Protocol (RDP) Information Disclosure Vulnerability
• CVE-2021-41371 – Windows Remote Desktop Protocol (RDP) Information Disclosure Vulnerability
• CVE-2021-43208 – 3D Viewer Remote Code Execution Vulnerability
• CVE-2021-43209 – 3D Viewer Remote Code Execution Vulnerability

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Recent updates from other companies

Other vendors who released updates in November include:

• Adobe’s November security updates were released for various applications.
• Android’s November security updates were released last week.
• Cisco released security updates for numerous products this month, including a hard-coded password and SSH key vulnerability.
• SAP released its November 2021 security updates.

The November 2021 Patch Tuesday Security Updates

Below is the complete list of resolved vulnerabilities and released advisories in the November 2021 Patch Tuesday updates. To access the full description of each vulnerability and the systems that it affects, you can view the full report here.

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Tag	CVE ID	CVE Title	Severity
3D Viewer	CVE-2021-43209	3D Viewer Remote Code Execution Vulnerability	Important
3D Viewer	CVE-2021-43208	3D Viewer Remote Code Execution Vulnerability	Important
Azure	CVE-2021-41373	FSLogix Information Disclosure Vulnerability	Important
Azure RTOS	CVE-2021-42303	Azure RTOS Elevation of Privilege Vulnerability	Important
Azure RTOS	CVE-2021-42302	Azure RTOS Elevation of Privilege Vulnerability	Important
Azure RTOS	CVE-2021-42301	Azure RTOS Information Disclosure Vulnerability	Important
Azure RTOS	CVE-2021-42323	Azure RTOS Information Disclosure Vulnerability	Important
Azure RTOS	CVE-2021-26444	Azure RTOS Information Disclosure Vulnerability	Important
Azure RTOS	CVE-2021-42304	Azure RTOS Elevation of Privilege Vulnerability	Important
Azure Sphere	CVE-2021-41374	Azure Sphere Information Disclosure Vulnerability	Important
Azure Sphere	CVE-2021-41376	Azure Sphere Information Disclosure Vulnerability	Important
Azure Sphere	CVE-2021-42300	Azure Sphere Tampering Vulnerability	Important
Azure Sphere	CVE-2021-41375	Azure Sphere Information Disclosure Vulnerability	Important
Microsoft Dynamics	CVE-2021-42316	Microsoft Dynamics 365 (on-premises) Remote Code Execution Vulnerability	Critical
Microsoft Edge (Chromium-based) in IE Mode	CVE-2021-41351	Microsoft Edge (Chrome based) Spoofing on IE Mode	Important
Microsoft Exchange Server	CVE-2021-42305	Microsoft Exchange Server Spoofing Vulnerability	Important
Microsoft Exchange Server	CVE-2021-41349	Microsoft Exchange Server Spoofing Vulnerability	Important
Microsoft Exchange Server	CVE-2021-42321	Microsoft Exchange Server Remote Code Execution Vulnerability	Important
Microsoft Office Access	CVE-2021-41368	Microsoft Access Remote Code Execution Vulnerability	Important
Microsoft Office Excel	CVE-2021-40442	Microsoft Excel Remote Code Execution Vulnerability	Important
Microsoft Office Excel	CVE-2021-42292	Microsoft Excel Security Feature Bypass Vulnerability	Important
Microsoft Office Word	CVE-2021-42296	Microsoft Word Remote Code Execution Vulnerability	Important
Microsoft Windows	CVE-2021-41356	Windows Denial of Service Vulnerability	Important
Microsoft Windows Codecs Library	CVE-2021-42276	Microsoft Windows Media Foundation Remote Code Execution Vulnerability	Important
Power BI	CVE-2021-41372	Power BI Report Server Spoofing Vulnerability	Important
Role: Windows Hyper-V	CVE-2021-42284	Windows Hyper-V Denial of Service Vulnerability	Important
Role: Windows Hyper-V	CVE-2021-42274	Windows Hyper-V Discrete Device Assignment (DDA) Denial of Service Vulnerability	Important
Visual Studio	CVE-2021-3711	OpenSSL: CVE-2021-3711 SM2 Decryption Buffer Overflow	Critical
Visual Studio	CVE-2021-42319	Visual Studio Elevation of Privilege Vulnerability	Important
Visual Studio Code	CVE-2021-42322	Visual Studio Code Elevation of Privilege Vulnerability	Important
Windows Active Directory	CVE-2021-42278	Active Directory Domain Services Elevation of Privilege Vulnerability	Important
Windows Active Directory	CVE-2021-42291	Active Directory Domain Services Elevation of Privilege Vulnerability	Important
Windows Active Directory	CVE-2021-42287	Active Directory Domain Services Elevation of Privilege Vulnerability	Important
Windows Active Directory	CVE-2021-42282	Active Directory Domain Services Elevation of Privilege Vulnerability	Important
Windows COM	CVE-2021-42275	Microsoft COM for Windows Remote Code Execution Vulnerability	Important
Windows Core Shell	CVE-2021-42286	Windows Core Shell SI Host Extension Framework for Composable Shell Elevation of Privilege Vulnerability	Important
Windows Cred SSProvider Protocol	CVE-2021-41366	Credential Security Support Provider Protocol (CredSSP) Elevation of Privilege Vulnerability	Important
Windows Defender	CVE-2021-42298	Microsoft Defender Remote Code Execution Vulnerability	Critical
Windows Desktop Bridge	CVE-2021-36957	Windows Desktop Bridge Elevation of Privilege Vulnerability	Important
Windows Diagnostic Hub	CVE-2021-42277	Diagnostics Hub Standard Collector Elevation of Privilege Vulnerability	Important
Windows Fastfat Driver	CVE-2021-41377	Windows Fast FAT File System Driver Elevation of Privilege Vulnerability	Important
Windows Feedback Hub	CVE-2021-42280	Windows Feedback Hub Elevation of Privilege Vulnerability	Important
Windows Hello	CVE-2021-42288	Windows Hello Security Feature Bypass Vulnerability	Important
Windows Installer	CVE-2021-41379	Windows Installer Elevation of Privilege Vulnerability	Important
Windows Kernel	CVE-2021-42285	Windows Kernel Elevation of Privilege Vulnerability	Important
Windows NTFS	CVE-2021-42283	NTFS Elevation of Privilege Vulnerability	Important
Windows NTFS	CVE-2021-41370	NTFS Elevation of Privilege Vulnerability	Important
Windows NTFS	CVE-2021-41378	Windows NTFS Remote Code Execution Vulnerability	Important
Windows NTFS	CVE-2021-41367	NTFS Elevation of Privilege Vulnerability	Important
Windows RDP	CVE-2021-38665	Remote Desktop Protocol Client Information Disclosure Vulnerability	Important
Windows RDP	CVE-2021-38631	Windows Remote Desktop Protocol (RDP) Information Disclosure Vulnerability	Important
Windows RDP	CVE-2021-38666	Remote Desktop Client Remote Code Execution Vulnerability	Critical
Windows RDP	CVE-2021-41371	Windows Remote Desktop Protocol (RDP) Information Disclosure Vulnerability	Important
Windows Scripting	CVE-2021-42279	Chakra Scripting Engine Memory Corruption Vulnerability	Critical
Windows Virtual Machine Bus	CVE-2021-26443	Microsoft Virtual Machine Bus (VMBus) Remote Code Execution Vulnerability	Critical