KB5120705: Cumulative update for .NET Framework, versions 3.5 and 4.8, on Windows Server 2022, August 2026. Six .NET vulnerabilities addressed; later updates fix WPF errors

Addresses six .NET Framework vulnerabilities. Some WPF printing errors caused by the update are resolved in later updates.

Does it affect you? Applies to: Windows Server 2022 x64 devices with .NET Framework 3.5 or 4.8 installed.

What changes

Fixes 6 changes

.NET Framework

6 items

For: Devices with .NET Framework 3.5 or 4.8 installed

Addresses an elevation-of-privilege vulnerability in .NET Framework.¹
CVE-2026-65810.
Addresses an elevation-of-privilege vulnerability in .NET Framework.²
CVE-2026-62872.
Addresses a remote code execution vulnerability in .NET Framework.³
CVE-2026-62886.
Addresses a remote code execution vulnerability in .NET Framework.⁴
CVE-2026-62897.
Addresses a remote code execution vulnerability in .NET Framework.⁵
CVE-2026-70354.
Addresses an information disclosure vulnerability in .NET Framework.⁶
CVE-2026-62902.

Known issues

Resolved Affects: Everyone

After installing the August 2026 .NET Framework cumulative update, some WPF applications may fail with a System.IO.File…

After this update, some WPF applications might fail with a System.IO.FileFormatException when printing or generating PDF/XPS content that uses certain fonts, including Calibri. The issue is resolved in the September 2026 .NET Framework cumulative update and later updates.⁷

How to apply the workaround Workaround

Temporarily enable the Switch.MS.Internal.TtfDelta.DisableCmapAndSbitOverflowProtection AppContext switch in the app config file, only when needed.⁷
Resolved Affects: Everyone

After installing the August 2026 .NET Framework cumulative update, WPF applications that print—or display print preview…

After this update, WPF applications that print or show print preview for certain in-memory XPS documents might fail with a System.IO.FileFormatException. The issue is resolved in the October 2026 .NET Framework cumulative update and later updates.⁸

How to apply the workaround Workaround

If the application can be rebuilt, use an absolute package identity without the pack scheme. Otherwise, temporarily enable the Switch.System.Windows.DisableXpsPackageBoundaryRestriction AppContext switch in the application config file.⁸
Step-by-step workaround instructions
2 steps

Show steps Hide steps
Step-by-step procedure
1. If the application can be rebuilt, replace the absolute package identity using the pack scheme with one such as xpspack://<guid>.xps.
2. If the application cannot be rebuilt, add Switch.System.Windows.DisableXpsPackageBoundaryRestriction=true to AppContextSwitchOverrides in the application config file.

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released: 2026-08-11
Classification: Security Updates
Type: Cumulative update
Restart: Required
Replaces: KB5101010, KB5087068
Replaced by: KB5126050

Version	File version	Channel
3.5	2.0.50727.9183	General availability
4.8	4.8.4805.0	General availability

Security

6 vulnerabilities fixed

4 important 2 not rated

Vulnerability	Severity	CVSS
CVE-2026-62872 .NET Framework Elevation of Privilege Vulnerability	Important	8.8
CVE-2026-65810 .NET Framework Elevation of Privilege Vulnerability	Important	7.8
CVE-2026-70354 .NET Core Remote Code Execution Vulnerability	Important	7.8
CVE-2026-62897 .NET Framework Remote Code Execution Vulnerability	Important	7.0
CVE-2026-62886 .NET Elevation of Privilege Vulnerability	Not rated	—
CVE-2026-62902 .NET Information Disclosure Vulnerability	Not rated	—

Downloads (Microsoft Update Catalog)

x64 Windows Server 2022

76.3 MB

windows10.0-kb5120705-x64-ndp48.msu Main update · KB5120705 SHA-1: bb301675…b33367

Updated components

66 files changed since the previous update for the same versions.

Top changed components	Files
WPF	28
ASP.NET	12
.NET runtime (CLR)	4

Page history

Nov 11, 2026

Added CVE-2026-62897 (Important)

Sources

Microsoft Support: KB5120705

Updated Nov 11, 2026

Cited passages from Microsoft's official notes (8)

1. This security update addresses an elevation of privilege vulnerability detailed in CVE-2026-65810. support.microsoft.com
2. This security update addresses an elevation of privilege vulnerability detailed in CVE-2026-62872. support.microsoft.com
3. This security update addresses a remote code execution vulnerability detailed in CVE-2026-62886. support.microsoft.com
4. This security update addresses a remote code execution vulnerability detailed in CVE-2026-62897. support.microsoft.com
5. This security update addresses a remote code execution vulnerability detailed in CVE-2026-70354. support.microsoft.com
6. This security update addresses an information disclosure vulnerability detailed in CVE-2026-62902. support.microsoft.com
7. After installing the August 2026 .NET Framework cumulative update, some WPF applications may fail with a System.IO.FileFormatException when printing or generating PDF/XPS content that uses certain fonts, including Calibri. support.microsoft.com
8. After installing the August 2026 .NET Framework cumulative update, WPF applications that print—or display print preview—from an in-memory XPS document registered with System.IO.Packaging.PackageStore may fail with a System.IO.FileFormatException while the document is loading. support.microsoft.com

Checked automatically: 7 of 8 checks passed, 8 quoted passages · compared with Microsoft's page on Oct 16, 2026

Quotes found in the official pages: passed
Numbers found in the sources: passed
Vulnerabilities from the dossier only: passed
Links to allowed domains only: passed
Every official change covered: passed
Readable plain text: passed
Changes confirmed by the file list: passed
Sources agree: not passed

A second AI read the text against the sources: correctness 5/5, clarity 4/5, completeness 4/5. How we work

Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake