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.NET Framework 4.8.1

.NET Framework 4.8.1

Every published release for .NET Framework 4.8.1, newest first: what each update changes, whether to install it and any confirmed known issues.

Latest
KB5127694 Oct 13, 2026
File version
4.8.10008.0
Released
Aug 9, 2022
Known issues
1 open

Update history

  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 21H2, 22H2 Update

    KB5042097

    ASP.NET compilation conflicts and UI automation rendering addressed

    Addresses .NET Framework reliability issues, including UI automation rendering and compilation conflicts that could slow work on large projects.

    Check the newer update, KB5044029

    Key changes 5 changes

    • Fix .NET Libraries: The update addresses an issue with bringing the zlib file up to its latest version.
    • Fix .NET Fundamentals: The update addresses a problem rendering ListView subitems used by UI automation.
    • Fix .NET Fundamentals: The update addresses an issue involving a serialization binder bypass through BinaryFormatter mutations.

    Read update Source: Microsoft

    Builds
    4.8.9261.0 · 2.0.50727.9179
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows Server 2022 Update

    KB5041964

    Fixes ListView rendering and ASP.NET project slowdowns

    Addresses reliability issues in .NET Framework, including ListView rendering and slowdowns in some large ASP.NET projects. It includes previously released security improvements but no new ones.

    Check the newer update, KB5044035

    Key changes 5 changes

    • Improved .NET Libraries: The update replaces a zlib file with the latest version.
    • Fix .NET Fundamentals: Automated tools can render the smaller entries inside a list view.
    • Fix .NET Fundamentals: The update addresses a case where modifying binary-formatted data could bypass a check before the data was read.

    Read update Source: Microsoft

    Builds
    4.8.9266.0 · 2.0.50727.9179
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 22H2 Optional preview
    Preview

    KB5041168

    ListView rendering, zlib, and ASP.NET issues addressed

    Addresses several .NET Framework reliability issues, including ListView rendering, serialization, and ASP.NET project compilation problems.

    Key changes 5 changes

    • Fix .NET Libraries: The update addresses an issue with bringing the zlib file up to its latest version.
    • Fix .NET Fundamentals: The update addresses a problem that could prevent UI automation from rendering ListView subitems.
    • Fix .NET Fundamentals: The update addresses an issue where binary formatter mutations could bypass the serialization binder.

    Read update Source: Microsoft

    Builds
    4.8.9261.0 · 2.0.50727.9177
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 21H2, 22H2 Security update

    KB5039893

    Elevation flaw fixed; temporary-path behavior changes

    CVE-2024-38081 is addressed. On Windows versions that expose `GetTempPath2`, `System.IO.Path.GetTempPath` can return a different path for SYSTEM processes, so affected software may need changes.

    Check the newer update, KB5044029

    Key changes 1 CVE · 3 changes

    • Fix .NET Framework: The update addresses an elevation-of-privilege vulnerability.
    • Fix WinForms: Addresses an issue with memory leaks associated with objects held in memory.
    • Fix .NET Fundamentals: Addresses an issue using X.509 certificates under PPL in Azure AD.

    Read update Source: Microsoft

    Builds
    4.8.9256.0 · 2.0.50727.9177
    Security
    1 vulnerability fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows Server 2022 Security update

    KB5039907

    Temporary-path behavior changes alongside a privilege fix

    The update fixes an elevation-of-privilege vulnerability in .NET Framework and changes the temporary path returned by System.IO.Path.GetTempPath, which might require affected applications to adapt.

    Check the newer update, KB5044035

    Key changes 1 CVE · 4 changes

    • Improved System.IO.Path.GetTempPath: Some applications might get a different temporary-folder path. Affected software is expected to change its code to adapt.
    • Fix .NET Framework: An elevation-of-privilege vulnerability in .NET Framework is addressed.
    • Fix Winforms: An issue with memory leaks involving AccessibleObjects held in memory is addressed.

    Read update Source: Microsoft

    Builds
    4.8.9256.0 · 2.0.50727.9177
    Security
    1 vulnerability fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 22H2 Optional preview
    Preview

    KB5039865

    WinForms memory leaks and Azure AD certificate use addressed

    Addresses memory leaks involving Windows Forms accessibility objects and an issue using x509 certificates under PPL in Azure AD. It contains no new security improvements.

    Key changes 2 changes

    • Fix Winforms: Addresses an issue involving the size of memory leaks from accessibility objects held in memory.
    • Fix .NET Fundamentals: Addresses an issue with using x509 certificates under PPL in Azure AD.

    Read update Source: Microsoft

    Builds
    4.8.9251.0 · 2.0.50727.9176
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 21H2, 22H2 Optional preview
    Preview

    KB5037587

    WPF crashes and CLR query errors addressed

    Addresses reliability issues in .NET Framework, including app crashes in WPF and the CLR. It adds no new security improvements.

    Check the newer update, KB5039893

    Key changes 6 changes

    • Fix CLR: Addresses a problem that can cause crashes when several threads query the same managed type.
    • Fix CLR: Addresses cases where symbol-reading APIs might return incorrect results.
    • Fix .NET Libraries: Addresses an issue that can be triggered in the FBX file parser.

    Read update Source: Microsoft

    Builds
    4.8.9241.0 · 2.0.50727.9176
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows Server 2022 Update

    KB5037929

    WPF window-text crashes and .NET runtime errors addressed

    Apps that read window text can crash, and some SQL CLR apps can hit runtime errors with specific hash types. This update also addresses issues in IIS 10 and .NET libraries.

    Check the newer update, KB5039907

    Key changes 6 changes

    • Fix CLR: Crashes from simultaneous queries of the same managed type are addressed.
    • Fix CLR: Two APIs that find methods by document position can return incorrect results in some cases; this issue is addressed.
    • Fix .NET Libraries: An issue in the FBX file parser is addressed.

    Read update Source: Microsoft

    Builds
    4.8.9246.0 · 2.0.50727.9176
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 21H2, 22H2 Security update

    KB5036618

    Remote code execution flaw addressed; .NET reliability issues improved

    Addresses CVE-2024-21409, a .NET Framework remote code execution vulnerability, and several reliability and performance issues in ASP.NET, the CLR, and the C# compiler.

    Check the newer update, KB5039893

    Key changes 1 CVE · 7 changes

    • Fix .NET Framework: Addresses a remote code execution vulnerability in .NET Framework.
    • Fix .NET Framework: Addresses an issue caused by an outdated version of the OSS zlib library.
    • Fix .NET Framework: Addresses an issue in the AIA fetching process.

    Read update Source: Microsoft

    Security
    1 vulnerability fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows Server 2022 Security update

    KB5036621

    Remote code execution flaw and application slowdowns addressed

    The update addresses CVE-2024-21409, a .NET Framework flaw that could let an attacker run code, and addresses several reliability and performance problems.

    Check the newer update, KB5039907

    Key changes 1 CVE · 7 changes

    • Fix .NET Framework: A security flaw that could let an attacker run code is addressed.
    • Fix .NET Framework: A security issue involving an outdated library used by .NET is addressed.
    • Fix .NET Framework: A security issue in a .NET data-fetching process is addressed.

    Read update Source: Microsoft

    Builds
    4.8.9236.0 · 2.0.50727.9176
    Security
    1 vulnerability fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 22H2 Optional preview
    Preview

    KB5036034

    ASP.NET performance and .NET runtime issues addressed

    Addresses a performance issue in ASP.NET and several .NET runtime and compiler issues. A restart is required if affected files are in use.

    Key changes 4 changes

    • Fix .NET Libraries: Addresses a performance issue in ASP.NET applications after installing the January 2024 .NET Framework update.
    • Fix .NET Runtime: Addresses an issue that can make thread pool recycled lists unresponsive on computers with multiple CPU groups.
    • Fix .NET Runtime: Addresses an issue where Interlocked.Read from 32-bit apps runs much slower on some computers.

    Read update Source: Microsoft

    Builds
    4.8.9232.0 · 2.0.50727.9176
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 21H2, 22H2 Optional preview
    Preview

    KB5034466

    ASP.NET path errors and an outdated zlib version addressed

    The update addresses an illegal-path error in some ASP.NET MVC requests and an outdated OSS zlib library version in .NET.

    Check the newer update, KB5036618

    Key changes 2 changes

    • Fix ASP.NET: An issue with an “Illegal characters in path” error in some ASP.NET MVC requests is addressed.
    • Fix .NET Libraries: An issue with an out-of-date zlib library version in .NET is addressed.

    Read update Source: Microsoft

    Builds
    4.8.9220.0 · 2.0.50727.9176
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows Server 2022 Update

    KB5034611

    ASP.NET path errors addressed; outdated zlib library

    Addresses an “Illegal characters in path” error in some ASP.NET MVC requests and an issue with an outdated zlib library.

    Check the newer update, KB5036621

    Key changes 2 changes

    • Fix ASP.NET: The update addresses an “Illegal characters in path” error in some ASP.NET MVC requests.
    • Fix .NET Libraries: The update addresses an issue with an outdated zlib library.

    Read update Source: Microsoft

    Builds
    4.8.9224.0 · 2.0.50727.9176
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 21H2, 22H2 Security update

    KB5033918

    Denial-of-service and privilege vulnerabilities addressed

    The update addresses four vulnerabilities, none rated critical, in .NET Framework. It also addresses a remote code execution vulnerability in an HTTP .NET remoting server channel chain.

    Check the newer update, KB5036618

    Key changes 4 CVEs · 5 changes

    • Fix .NET Framework: A .NET Framework denial-of-service vulnerability is addressed.
    • Fix .NET Framework: A .NET Framework security feature bypass vulnerability is addressed.
    • Fix .NET Framework: A .NET Framework elevation-of-privilege vulnerability is addressed.

    Read update Source: Microsoft

    Builds
    4.8.9214.0 · 2.0.50727.9176
    Security
    4 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows Server 2022 Security update

    KB5033922

    Denial-of-service and remote-code-execution flaws addressed

    The update addresses 4 vulnerabilities in .NET Framework 3.5 and 4.8.1, including flaws that could disrupt services or let attackers run code remotely.

    Check the newer update, KB5036621

    Key changes 4 CVEs · 5 changes

    • Fix .NET Framework: The update addresses a flaw that could disrupt a service.
    • Fix .NET Framework: The update blocks a flaw that could let an attacker get around a security feature.
    • Fix .NET Framework: The update addresses a flaw that could let an attacker gain higher access.

    Read update Source: Microsoft

    Builds
    4.8.9214.0 · 2.0.50727.9176
    Security
    4 vulnerabilities fixed
    Restart
    Required