The Update BureauKB5120698: Cumulative update for .NET Framework, versions 3.5 and 4.7.2, on Windows 10 1809 and Windows Server 2019, August 2026. Six .NET vulnerabilities addressed; WPF issues resolved later
The update addresses six .NET Framework vulnerabilities. Two WPF printing issues were later resolved in the September and October 2026 cumulative updates.
Does it affect you? Applies to: Devices running Windows 10, version 1809, or Windows Server 2019 with .NET Framework 3.5 or 4.7.2 installed.
What changes
Improvements 6 changes
.NET Framework
For: Devices with .NET Framework 3.5 or 4.7.2
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The update addresses a .NET Framework elevation-of-privilege vulnerability.1
CVE-2026-65810.
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The update addresses a .NET Framework elevation-of-privilege vulnerability.2
CVE-2026-62872.
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The update addresses a .NET Framework remote-code-execution vulnerability.3
CVE-2026-62886.
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The update addresses a .NET Framework remote-code-execution vulnerability.4
CVE-2026-62897.
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The update addresses a .NET Framework remote-code-execution vulnerability.5
CVE-2026-70354.
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The update addresses a .NET Framework information-disclosure vulnerability.6
CVE-2026-62902.
Known issues
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After installing the August 2026 .NET Framework cumulative update, some WPF applications may fail with a System.IO.File…
After the August 2026 update, some WPF applications might fail with a
System.IO.FileFormatExceptionwhen 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.7How to apply the workaround WorkaroundTemporarily enable the AppContext switch in the application config file; Microsoft warns this disables security protections and may increase exposure to the vulnerabilities addressed by the update.7
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After installing the August 2026 .NET Framework cumulative update, WPF applications that print—or display print preview…
After the August 2026 update, WPF applications might fail to print or show print preview for some in-memory XPS documents registered with
System.IO.Packaging.PackageStore. The issue is resolved in the October 2026 .NET Framework cumulative update and later updates.8How to apply the workaround WorkaroundRebuild affected applications with an absolute package identity that does not use the
packscheme. If an application cannot be rebuilt, temporarily enable the AppContext switch; Microsoft warns that it disables security protections and may increase exposure to the vulnerabilities addressed by the update.8Step-by-step workaround instructionsShow steps Hide steps2 stepsStep-by-step procedure- For applications that can be rebuilt, use an absolute package identity such as
xpspack://<guid>.xpsinstead of apackscheme identity. - For applications that cannot be rebuilt, add
Switch.System.Windows.DisableXpsPackageBoundaryRestriction=truetoAppContextSwitchOverridesin the application config file.
- For applications that can be rebuilt, use an absolute package identity such as
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
- KB5100989, KB5087061
- Replaced by
- KB5126043
| Version | File version | Channel |
|---|---|---|
| 3.5 | 2.0.50727.9070 | General availability |
| 4.7.2 | 4.7.4144.0 | General availability |
Security
| Vulnerability | Severity | CVSS |
|---|---|---|
|
.NET Framework Elevation of Privilege Vulnerability
|
Important | 8.8 |
|
.NET Framework Elevation of Privilege Vulnerability
|
Important | 7.8 |
|
.NET Core Remote Code Execution Vulnerability
|
Important | 7.8 |
|
.NET Framework Remote Code Execution Vulnerability
|
Important | 7.0 |
|
.NET Elevation of Privilege Vulnerability
|
Not rated | — |
|
.NET Information Disclosure Vulnerability
|
Not rated | — |
Downloads (Microsoft Update Catalog)
Updated components
99 files changed since the previous update for the same versions.
| Top changed components | Files |
|---|---|
| WPF | 42 |
| ASP.NET | 18 |
| .NET runtime (CLR) | 6 |
Sources
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.
This issue is resolved in the September 2026 .NET Framework cumulative update and later updates.
support.microsoft.com -
8.
This issue is resolved in the October 2026 .NET Framework cumulative update and later updates.
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 3/5, 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