The Update BureauKB5120710: Cumulative update for .NET Framework, versions 3.5 and 4.8.1, on Windows 11 24H2, August 2026. Six runtime flaws addressed; WPF print errors need later updates
Addresses six .NET Framework vulnerabilities. Two WPF printing problems are resolved only by later cumulative updates.
Does it affect you? Applies to: Devices running Windows 11, version 24H2, with .NET Framework 3.5 or 4.8.1 installed. Packages are available for x64 and Arm64.
What changes
Fixes 6 changes
.NET Framework
For: devices with .NET Framework installed
-
Addresses an elevation-of-privilege vulnerability in .NET Framework.1
CVE-2026-65810.
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Addresses an elevation-of-privilege vulnerability in .NET Framework.2
CVE-2026-62872.
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Addresses a remote code execution vulnerability in .NET Framework.3
CVE-2026-62886.
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Addresses a remote code execution vulnerability in .NET Framework.4
CVE-2026-62897.
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Addresses a remote code execution vulnerability in .NET Framework.5
CVE-2026-70354.
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Addresses an information disclosure vulnerability in .NET Framework.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…
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 WorkaroundAs a temporary measure, enable the specified AppContext switch in the application configuration file only when needed to address the issue.7
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After installing the August 2026 .NET Framework cumulative update, WPF applications that print—or display print preview…
WPF applications that print or show print preview from an in-memory XPS document registered with
System.IO.Packaging.PackageStoremight fail with a System.IO.FileFormatException while the document loads. This occurs when the absolute pack-scheme URI is used both as the PackageStore key and as the XpsDocument package identity. The issue is resolved in the October 2026 .NET Framework cumulative update and later updates.8How to apply the workaround WorkaroundFor applications that can be rebuilt, use an absolute package identity that does not use the pack scheme, such as
xpspack://<guid>.xps. If an application cannot be rebuilt, enable the specified AppContext switch in its configuration file, temporarily and only when needed.8Step-by-step workaround instructionsShow steps Hide steps2 stepsStep-by-step procedure- If the application can be rebuilt, change its absolute package identity to one that does not use the pack scheme, such as
xpspack://<guid>.xps. - If the application cannot be rebuilt, enable
Switch.System.Windows.DisableXpsPackageBoundaryRestrictionin the application configuration file.
- If the application can be rebuilt, change its absolute package identity to one that does not use the pack scheme, 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
- KB5101001, KB5092430, KB5087054, KB5082420
- Replaced by
- KB5126052
| Version | File version | Channel |
|---|---|---|
| 3.5 | 2.0.50727.9183 | General availability |
| 4.8.1 | 4.8.9343.0 | 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
79 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
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Added CVE-2026-62897 (Important)
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 occurs when the package identity used as both the PackageStore key and the XpsDocument package identity is an absolute URI that uses the pack scheme—for example,
support.microsoft.compack://<guid>.xps.
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 5/5. 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