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.NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 Security update
Patch Tuesday

KB5120708

KB5120708: Cumulative update for .NET Framework, versions 3.5 and 4.8.1, on Windows 11 25H2 and Windows Server 2025, August 2026. Six runtime vulnerabilities addressed; WPF print failures later resolved

In short

The update addresses six .NET Framework vulnerabilities. Two WPF printing failures reported after installation are resolved by later updates: one in September and one in October 2026.

Does it affect you? Applies to: Devices running Windows 11, version 25H2, or Microsoft server operating system 24H2 (Windows Server 2025), with .NET Framework 3.5 or 4.8.1 installed. Packages are available for x64 and Arm64.

File version
2.0.50727.9183 · 4.8.9344.0
Security
6 fixed
Restart
Required

What changes

Fixes 6 changes

.NET Framework

6 items

For: devices with .NET Framework 3.5 or 4.8.1 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

  1. Resolved Affects: Everyone

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

    Some WPF applications can fail with a System.IO.FileFormatException when printing or generating PDF/XPS content with certain fonts, including Calibri. The issue is resolved by the September 2026 .NET Framework cumulative update and later updates.7

    How to apply the workaround Workaround

    Applications can temporarily enable the Switch.MS.Internal.TtfDelta.DisableCmapAndSbitOverflowProtection AppContext switch in their app config file when needed.7

  2. Resolved Affects: Everyone

    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 for certain in-memory XPS documents can fail with a System.IO.FileFormatException while loading the document. The issue is resolved by the October 2026 .NET Framework cumulative update and later updates.8

    How to apply the workaround Workaround

    For applications that can be rebuilt, use an absolute package identity that does not use the pack scheme. If an application cannot be rebuilt, enable the Switch.System.Windows.DisableXpsPackageBoundaryRestriction AppContext switch in its configuration file.8

    Step-by-step workaround instructions
    2 steps
    Show steps Hide steps
    Step-by-step procedure
    1. If the application can be rebuilt, change the absolute package identity to one that does not use the pack scheme, such as xpspack://<guid>.xps.
    2. If the application cannot be rebuilt, enable Switch.System.Windows.DisableXpsPackageBoundaryRestriction in its application configuration 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
KB5100998, KB5092427, KB5087051, KB5082417
+11 earlier KB5074828, KB5067931, KB5066128, KB5066131, KB5066613, KB5064401, KB5056579, KB5054979, KB5049622, KB5045934, KB5044030
Replaced by
KB5126052
VersionFile versionChannel
3.5 2.0.50727.9183 General availability
4.8.1 4.8.9344.0 General availability

Security

6 vulnerabilities fixed
4 important 2 not rated
VulnerabilitySeverityCVSS
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 2025 / Windows 11, version 25H2
92.3 MB
windows11.0-kb5120708-x64-ndp481.msu Main update · KB5120708 SHA-1: 220a883c…93a611
Arm64 Windows Server 2025 / Windows 11, version 25H2
110.6 MB
windows11.0-kb5120708-arm64-ndp481.msu Main update · KB5120708 SHA-1: 7cefdbc9…3a7e3a

Updated components

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

Top changed componentsFiles
WPF28
ASP.NET12
.NET runtime (CLR)4

Page history

  1. Added CVE-2026-62897 (Important)

Sources

Updated
Cited passages from Microsoft's official notes (8)
  1. 1. This security update addresses an elevation of privilege vulnerability detailed in [CVE-2026-65810.] support.microsoft.com
  2. 2. This security update addresses an elevation of privilege vulnerability detailed in [CVE-2026-62872.] support.microsoft.com
  3. 3. This security update addresses a remote code execution vulnerability detailed in [CVE-2026-62886.] support.microsoft.com
  4. 4. This security update addresses a remote code execution vulnerability detailed in [CVE-2026-62897.] support.microsoft.com
  5. 5. This security update addresses a remote code execution vulnerability detailed in [CVE-2026-70354.] support.microsoft.com
  6. 6. This security update addresses an information disclosure vulnerability detailed in [CVE-2026-62902.] support.microsoft.com
  7. 7. Applications may mitigate the issue by enabling the Switch.MS.Internal.TtfDelta.DisableCmapAndSbitOverflowProtection AppContext switch in the app config file, as shown below. support.microsoft.com
  8. 8. Applications that can be rebuilt should use an absolute package identity that does not use the pack scheme—for example, xpspack://<guid>.xps. support.microsoft.com
Checked automatically: 7 of 8 checks passed, 8 quoted passages · compared with Microsoft's page on Oct 20, 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