Microsoft October 2021 Patch Tuesday

This month we got patches for 81 vulnerabilities. Of these, 3 are critical, 3 were previously disclosed and 1 is being exploited according to Microsoft.

The exploited vulnerability (CVE-2021-40449) is an elevation of privilege affecting Win32k on virtually all supported Windows versions. According to the advisory, a local attacker may elevate privileges with no user interactions. 

Among critical vulnerabilities, there are two Windows Hyper-V Remote Code Execution Vulnerability (CVE-2021-40461 and CVE-2021-38672) affecting multiple versions of Windows 10, 11 and Server. An attacker within the same physical or logical network with low privileges and no user interaction could exploit this vulnerability to execute code on the targeted system. The CVSS V3 for both vulnerabilities is 8.0. The third critical vulnerabilty is the Microsoft Word Remote Code Execution Vulnerability (CVE-2021-40486) with the CVSS V3 of 7.8.

Another vulnerability worth mentioning due to recent vulnerabilities involving the print spooler, albeit without much detail, is the Windows Print Spooler Spoofing Vulnerability (CVE-2021-36970). The CVSS V3 for this vulnerability is 8.8 and the exploitability assessment is 'Exploitation more likely'.

The highest CVSS v3 this month (9.0) was associated to the Microsoft Exchange Server Remote Code Execution Vulnerability (CVE-2021-26427). According to the advisory, the attack vector for this vulnerablity is 'adjacent', which means the attack can not be done accross the internet. The vulnerabilty affects Windows Exchange Server on versions 2013, 2016 and 2019.

See my dashboard for a more detailed breakout: https://patchtuesdaydashboard.com/

October 2021 Security Updates

Description
CVE Disclosed Exploited Exploitability (old versions) current version Severity CVSS Base (AVG) CVSS Temporal (AVG)
.NET Core and Visual Studio Information Disclosure Vulnerability
CVE-2021-41355 No No Less Likely Less Likely Important 5.7 5.0
Active Directory Federation Server Spoofing Vulnerability
CVE-2021-41361 No No Less Likely Less Likely Important 5.4 4.7
Active Directory Security Feature Bypass Vulnerability
CVE-2021-41337 No No Less Likely Less Likely Important 4.9 4.3
Chromium: CVE-2021-37974 Use after free in Safe Browsing
CVE-2021-37974 No No - - -    
Chromium: CVE-2021-37975 Use after free in V8
CVE-2021-37975 No No - - -    
Chromium: CVE-2021-37976 Information leak in core
CVE-2021-37976 No No - - -    
Chromium: CVE-2021-37977 Use after free in Garbage Collection
CVE-2021-37977 No No - - -    
Chromium: CVE-2021-37978 Heap buffer overflow in Blink
CVE-2021-37978 No No - - -    
Chromium: CVE-2021-37979 Heap buffer overflow in WebRTC
CVE-2021-37979 No No - - -    
Chromium: CVE-2021-37980 Inappropriate implementation in Sandbox
CVE-2021-37980 No No - - -    
Console Window Host Security Feature Bypass Vulnerability
CVE-2021-41346 No No Less Likely Less Likely Important 5.3 4.6
DirectX Graphics Kernel Elevation of Privilege Vulnerability
CVE-2021-40470 No No More Likely More Likely Important 7.8 6.8
Intune Management Extension Security Feature Bypass Vulnerability
CVE-2021-41363 No No Less Likely Less Likely Important 4.2 3.8
Microsoft DWM Core Library Elevation of Privilege Vulnerability
CVE-2021-41339 No No Less Likely Less Likely Important 4.7 4.2
Microsoft Dynamics 365 (on-premises) Cross-site Scripting Vulnerability
CVE-2021-41354 No No - - Important 4.1 3.6
Microsoft Dynamics 365 (on-premises) Spoofing Vulnerability
CVE-2021-41353 No No - - Important 5.4 4.7
Microsoft Dynamics 365 Customer Engagement Cross-Site Scripting Vulnerability
CVE-2021-40457 No No Less Likely Less Likely Important 7.4 6.9
Microsoft Excel Information Disclosure Vulnerability
CVE-2021-40472 No No Less Likely Less Likely Important 5.5 4.8
Microsoft Excel Remote Code Execution Vulnerability
CVE-2021-40471 No No Less Likely Less Likely Important 7.8 6.8
CVE-2021-40473 No No Less Likely Less Likely Important 7.8 6.8
CVE-2021-40474 No No Less Likely Less Likely Important 7.8 6.8
CVE-2021-40479 No No Less Likely Less Likely Important 7.8 6.8
CVE-2021-40485 No No Less Likely Less Likely Important 7.8 6.8
Microsoft Exchange Server Denial of Service Vulnerability
CVE-2021-34453 No No Less Likely Less Likely Important 7.5 6.5
Microsoft Exchange Server Elevation of Privilege Vulnerability
CVE-2021-41348 No No Less Likely Less Likely Important 8.0 7.0
Microsoft Exchange Server Remote Code Execution Vulnerability
CVE-2021-26427 No No Less Likely Less Likely Important 9.0 7.8
Microsoft Exchange Server Spoofing Vulnerability
CVE-2021-41350 No No Less Likely Less Likely Important 6.5 5.7
Microsoft Office Visio Remote Code Execution Vulnerability
CVE-2021-40480 No No Less Likely Less Likely Important 7.8 6.8
CVE-2021-40481 No No Less Likely Less Likely Important 7.1 6.2
Microsoft SharePoint Server Information Disclosure Vulnerability
CVE-2021-40482 No No Less Likely Less Likely Important 5.3 4.8
Microsoft SharePoint Server Remote Code Execution Vulnerability
CVE-2021-41344 No No More Likely More Likely Important 8.1 7.1
CVE-2021-40487 No No More Likely More Likely Important 8.1 7.1
Microsoft SharePoint Server Spoofing Vulnerability
CVE-2021-40483 No No Less Likely Less Likely Low 7.6 6.6
CVE-2021-40484 No No Less Likely Less Likely Important 7.6 6.6
Microsoft Windows Media Foundation Remote Code Execution Vulnerability
CVE-2021-41330 No No Less Likely Less Likely Important 7.8 6.8
Microsoft Word Remote Code Execution Vulnerability
CVE-2021-40486 No No Less Likely Less Likely Critical 7.8 6.8
OpenSSL: CVE-2020-1971 EDIPARTYNAME NULL pointer de-reference
CVE-2020-1971 No No Less Likely Less Likely Important    
OpenSSL: CVE-2021-3449 NULL pointer deref in signature_algorithms processing
CVE-2021-3449 No No Less Likely Less Likely Important    
OpenSSL: CVE-2021-3450 CA certificate check bypass with X509_V_FLAG_X509_STRICT
CVE-2021-3450 No No Unlikely Unlikely Important    
Rich Text Edit Control Information Disclosure Vulnerability
CVE-2021-40454 No No Less Likely Less Likely Important 5.5 5.1
SCOM Information Disclosure Vulnerability
CVE-2021-41352 No No Less Likely Less Likely Important 7.5 6.5
Storage Spaces Controller Elevation of Privilege Vulnerability
CVE-2021-40478 No No Less Likely Less Likely Important 7.8 6.8
CVE-2021-40488 No No Less Likely Less Likely Important 7.8 6.8
CVE-2021-40489 No No Less Likely Less Likely Important 7.8 6.8
CVE-2021-26441 No No Less Likely Less Likely Important 7.8 6.8
CVE-2021-41345 No No Less Likely Less Likely Important 7.8 6.8
Win32k Elevation of Privilege Vulnerability
CVE-2021-40449 No Yes Detected Detected Important 7.8 7.2
CVE-2021-40450 No No More Likely More Likely Important 7.8 6.8
CVE-2021-41357 No No More Likely More Likely Important 7.8 7.2
Windows AD FS Security Feature Bypass Vulnerability
CVE-2021-40456 No No Less Likely Less Likely Important 5.3 4.6
Windows AppContainer Elevation Of Privilege Vulnerability
CVE-2021-40476 No No Less Likely Less Likely Important 7.5 6.7
Windows AppContainer Firewall Rules Security Feature Bypass Vulnerability
CVE-2021-41338 Yes No Less Likely Less Likely Important 5.5 5.0
Windows AppX Deployment Service Elevation of Privilege Vulnerability
CVE-2021-41347 No No Less Likely Less Likely Important 7.8 6.8
Windows Bind Filter Driver Information Disclosure Vulnerability
CVE-2021-40468 No No Less Likely Less Likely Important 5.5 4.8
Windows Cloud Files Mini Filter Driver Information Disclosure Vulnerability
CVE-2021-40475 No No Less Likely Less Likely Important 5.5 4.8
Windows Common Log File System Driver Elevation of Privilege Vulnerability
CVE-2021-40443 No No More Likely More Likely Important 7.8 6.8
CVE-2021-40466 No No More Likely More Likely Important 7.8 6.8
CVE-2021-40467 No No More Likely More Likely Important 7.8 6.8
Windows DNS Server Remote Code Execution Vulnerability
CVE-2021-40469 Yes No Less Likely Less Likely Important 7.2 6.5
Windows Desktop Bridge Elevation of Privilege Vulnerability
CVE-2021-41334 No No Less Likely Less Likely Important 7.0 6.1
Windows Event Tracing Elevation of Privilege Vulnerability
CVE-2021-40477 No No Less Likely Less Likely Important 7.8 6.8
Windows Fast FAT File System Driver Information Disclosure Vulnerability
CVE-2021-38662 No No Less Likely Less Likely Important 5.5 4.8
CVE-2021-41343 No No Less Likely Less Likely Important 5.5 4.8
Windows Graphics Component Remote Code Execution Vulnerability
CVE-2021-41340 No No Less Likely Less Likely Important 7.8 6.8
Windows HTTP.sys Elevation of Privilege Vulnerability
CVE-2021-26442 No No Less Likely Less Likely Important 7.0 6.1
Windows Hyper-V Remote Code Execution Vulnerability
CVE-2021-38672 No No Less Likely Less Likely Critical 8.0 7.0
CVE-2021-40461 No No Less Likely Less Likely Critical 8.0 7.0
Windows Installer Spoofing Vulnerability
CVE-2021-40455 No No Less Likely Less Likely Important 5.5 4.8
Windows Kernel Elevation of Privilege Vulnerability
CVE-2021-41335 Yes No Less Likely Less Likely Important 7.8 7.0
Windows Kernel Information Disclosure Vulnerability
CVE-2021-41336 No No Less Likely Less Likely Important 5.5 4.8
Windows MSHTML Platform Remote Code Execution Vulnerability
CVE-2021-41342 No No Less Likely Less Likely Important 6.8 6.1
Windows Media Audio Decoder Remote Code Execution Vulnerability
CVE-2021-41331 No No Less Likely Less Likely Important 7.8 6.8
Windows Media Foundation Dolby Digital Atmos Decoders Remote Code Execution Vulnerability
CVE-2021-40462 No No Less Likely Less Likely Important 7.8 6.8
Windows NAT Denial of Service Vulnerability
CVE-2021-40463 No No Less Likely Less Likely Important 7.7 6.7
Windows Nearby Sharing Elevation of Privilege Vulnerability
CVE-2021-40464 No No Less Likely Less Likely Important 8.0 7.0
Windows Print Spooler Information Disclosure Vulnerability
CVE-2021-41332 No No Less Likely Less Likely Important 6.5 5.7
Windows Print Spooler Spoofing Vulnerability
CVE-2021-36970 No No More Likely More Likely Important 8.8 8.2
Windows Remote Procedure Call Runtime Security Feature Bypass Vulnerability
CVE-2021-40460 No No Less Likely Less Likely Important 6.5 5.7
Windows TCP/IP Denial of Service Vulnerability
CVE-2021-36953 No No Less Likely Less Likely Important 7.5 6.5
Windows Text Shaping Remote Code Execution Vulnerability
CVE-2021-40465 No No Less Likely Less Likely Important 7.8 6.8
Windows exFAT File System Information Disclosure Vulnerability
CVE-2021-38663 No No Less Likely Less Likely Important 5.5 4.8

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Renato Marinho
Morphus Labs| LinkedIn|Twitter

 Renato

87 Posts
ISC Handler
Oct 12th 2021
Thread locked Subscribe Oct 12th 2021
11 months ago
Thank you for the information, I have a thought/question regarding your assessment. As you mentioned it only appears that perhaps one of the vulnerabilities show any type of real threat and it is marked as "Important", what factors would you use to determine if one should patch all their devices sooner than on a normal patch cycle? Typically a TVM team would evaluate vulnerabilities and unless they really pose a Zero-day alert, or the like, they maintain a normal monthly patch cycle. However, cve-2021-40449 seems like it should have been marked as "Critical" but was marked as "important" even though it has been exploited and requires local access. What additional evaluations or testing is recommended? Thanks,
 Anonymous
Quote Oct 18th 2021
11 months ago

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