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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

Latest update

  • KB5127694 Released Oct 13, 2026
    File version 4.8.10008.0

Update history

  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 26H2 Security update

    KB5127694

    Critical AD FS spoofing flaw and .NET security bypass addressed

    The update addresses 21 vulnerabilities, including a critical AD FS spoofing flaw and a publicly disclosed .NET security-feature bypass. It applies to .NET Framework 3.5 and 4.8.1 on Windows 11, version 26H2.

    Key changes 21 CVEs · 19 changes

    • Fix .NET Framework security: A flaw that could stop a service is addressed.
    • Fix .NET Framework security: A flaw that could give an attacker more access is addressed.
    • Fix .NET Framework security: A flaw that could stop a service is addressed.

    Read update Source: Microsoft

    Builds
    4.8.10008.0 · 2.0.50727.9188
    Security
    21 fixed · 1 critical
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 26H1 Security update

    KB5127691

    Critical AD FS spoofing flaw and public .NET bypass fixed

    Fixes 20 security flaws, including a Critical AD FS spoofing flaw and a publicly disclosed .NET Framework flaw that bypasses a security feature. Restart if affected files are in use.

    Key changes 20 CVEs · 19 changes

    • Fix .NET Framework: A .NET Framework flaw that could cause a denial of service is fixed.
    • Fix .NET Framework: A .NET Framework flaw that could let someone gain higher access is fixed.
    • Fix .NET Framework: A .NET Framework flaw that could cause a denial of service is fixed.

    Read update Source: Microsoft

    Build
    4.8.9363.0
    Security
    20 fixed · 1 critical
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 24H2, 25H2 · Windows Server 2025 Security update

    KB5127690

    Fixes 21 vulnerabilities (1 critical)

    Addresses a critical spoofing flaw and other security risks in .NET Framework. It covers 21 vulnerabilities, including one that was publicly disclosed.

    Key changes 21 CVEs · 19 changes

    • Fix .NET Framework: Helps prevent denial-of-service attacks on .NET Framework.
    • Fix .NET Framework: Helps stop attackers from gaining higher access through .NET Framework.
    • Fix .NET Framework: Helps prevent denial-of-service attacks on .NET Framework.

    Read update Source: Microsoft

    Builds
    4.8.9363.0 · 2.0.50727.9188
    Security
    21 fixed · 1 critical
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 23H2 Security update

    KB5127692

    Critical spoofing flaw and disclosed security bypass addressed

    The update addresses 21 vulnerabilities, including one critical flaw and a publicly disclosed security bypass. It also updates .NET Framework 3.5 and 4.8.1.

    Key changes 21 CVEs · 19 changes

    • Fix .NET Framework: A flaw that could stop a .NET app from responding is addressed.
    • Fix .NET Framework: A flaw that could let someone gain more control is addressed.
    • Fix .NET Framework: A flaw that could stop a .NET app from responding is addressed.

    Read update Source: Microsoft

    Builds
    4.8.9363.0 · 2.0.50727.9188
    Security
    21 fixed · 1 critical
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 21H2, 22H2 Security update

    KB5127689

    AD FS spoofing flaw and disclosed security bypass addressed

    Addresses 21 vulnerabilities. One is a critical AD FS spoofing flaw; another is a publicly disclosed .NET Framework security bypass.

    Key changes 21 CVEs · 19 changes

    • Fix .NET Framework: A denial-of-service flaw is addressed.
    • Fix .NET Framework: An elevation-of-privilege flaw is addressed.
    • Fix .NET Framework: A denial-of-service flaw is addressed.

    Read update Source: Microsoft

    Builds
    4.8.9363.0 · 2.0.50727.9188
    Security
    21 fixed · 1 critical
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows Server 2022 Security update

    KB5127693

    Spoofing flaw fixed alongside a security bypass

    The update fixes 21 flaws: 1 Critical, 18 Important, and 2 Unrated. They include spoofing flaw CVE-2026-96222 and publicly disclosed CVE-2026-108398, a security feature bypass.

    Key changes 21 CVEs · 19 changes

    • Fix .NET Framework: Fixes a flaw that could make a service stop responding.
    • Fix .NET Framework: Fixes a flaw that could let a user gain more access.
    • Fix .NET Framework: Fixes a flaw that could make a service stop responding.

    Read update Source: Microsoft

    Builds
    4.8.9363.0 · 2.0.50727.9188
    Security
    21 fixed · 1 critical
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 24H2, 25H2, 26H2 · Windows Server 2025 Security update

    KB5126052

    Two .NET vulnerabilities addressed; 64-bit crashes targeted

    The update addresses two Important .NET Framework vulnerabilities and an issue that could cause intermittent crashes in some 64-bit .NET Framework scenarios.

    Check the newer update, KB5127690

    Key changes 2 CVEs · 3 changes

    • Fix .NET Framework: Addresses an elevation-of-privilege vulnerability in .NET Framework.
    • Fix .NET Framework: Addresses a remote-code-execution vulnerability in .NET Framework.
    • Fix NET Fundamentals: Addresses an issue that could cause intermittent crashes in some 64-bit .NET Framework scenarios.

    Read update Source: Microsoft

    Builds
    4.8.9347.0 · 2.0.50727.9183
    Security
    2 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 26H1 Security update

    KB5126053

    Elevation-of-privilege and code-execution flaws addressed

    Addresses two Important .NET Framework vulnerabilities, including remote code execution, and intermittent crashes in some 64-bit scenarios.

    Check the newer update, KB5127691

    Key changes 2 CVEs · 3 changes

    • Fix .NET Framework: An elevation-of-privilege flaw is addressed.
    • Fix .NET Framework: A remote code execution flaw is addressed.
    • Fix NET Fundamentals: Intermittent crashes that could occur in some 64-bit .NET Framework scenarios are addressed.

    Read update Source: Microsoft

    Build
    4.8.9347.0
    Security
    2 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 23H2 Security update

    KB5126424

    Intermittent crashes in 64-bit .NET scenarios addressed

    The update addresses two .NET Framework security vulnerabilities and intermittent crashes in some 64-bit scenarios. A restart is required if affected files are in use.

    Check the newer update, KB5127692

    Key changes 2 CVEs · 3 changes

    • Fix .NET Framework: Addresses an elevation-of-privilege vulnerability in .NET Framework.
    • Fix .NET Framework: Addresses a remote code execution vulnerability in .NET Framework.
    • Fix NET Fundamentals: Intermittent crashes in some 64-bit .NET Framework scenarios are addressed.

    Read update Source: Microsoft

    Builds
    4.8.9346.0 · 2.0.50727.9183
    Security
    2 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 21H2, 22H2 Security update

    KB5126421

    Elevation-of-privilege and remote-code flaws addressed

    Addresses two Important .NET Framework vulnerabilities, including one that could let an attacker run code remotely. It also includes reliability improvements.

    Check the newer update, KB5127689

    Key changes 2 CVEs · 3 changes

    • Improved .NET Framework: Reliability improves for .NET Framework 3.5 and 4.8.1.
    • Fix .NET Framework: The update addresses a flaw that could let an attacker gain higher privileges.
    • Fix .NET Framework: The update addresses a flaw that could let an attacker run code remotely.

    Read update Source: Microsoft

    Builds
    4.8.9346.0 · 2.0.50727.9183
    Security
    2 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows Server 2022 Security update

    KB5126422

    Remote code execution and privilege-escalation flaws addressed

    The update addresses two .NET vulnerabilities, including a remote code execution flaw. Microsoft later removed CVE-2026-62886 from the KB page’s vulnerability listing.

    Check the newer update, KB5127693

    Key changes 2 CVEs · 3 changes

    • Improved .NET Framework: Includes cumulative reliability improvements for .NET Framework 3.5 and 4.8.1.
    • Fix .NET Framework: Addresses a vulnerability that could let an attacker gain elevated privileges.
    • Fix .NET Framework: Addresses a vulnerability that could let an attacker run code remotely.

    Read update Source: Microsoft

    Builds
    4.8.9346.0 · 2.0.50727.9183
    Security
    2 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 26H1 Optional preview
    Preview

    KB5122386

    Intermittent crashes in 64-bit .NET scenarios addressed

    Addresses an issue that could cause intermittent crashes in some 64-bit .NET Framework scenarios. A restart is required after installation if affected files are in use.

    Check the newer update, KB5126053

    Key changes 1 change

    • Fix .NET Fundamentals: An issue that could cause intermittent crashes in some 64-bit .NET Framework scenarios is addressed.

    Read update Source: Microsoft

    Build
    4.8.9345.0
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 24H2, 25H2 Optional preview
    Preview

    KB5122385

    Intermittent crashes addressed in 64-bit .NET scenarios

    Addresses intermittent crashes in some 64-bit .NET Framework scenarios.

    Check the newer update, KB5126052

    Key changes 1 change

    • Improved .NET Fundamentals: Intermittent crashes might occur less often in some 64-bit .NET Framework scenarios.

    Read update Source: Microsoft

    Builds
    4.8.9345.0 · 2.0.50727.9183
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 26H1 Security update

    KB5120711

    Six vulnerabilities fixed; later updates resolve WPF print failures

    The update addresses six .NET Framework vulnerabilities. Two WPF printing failures were also reported; later cumulative updates resolve them.

    Check the newer update, KB5126053

    Key changes 6 CVEs · 6 changes

    • Fix .NET Framework: Addresses an elevation-of-privilege vulnerability in .NET Framework.
    • Fix .NET Framework: Addresses an elevation-of-privilege vulnerability in .NET Framework.
    • Fix .NET Framework: Addresses a remote-code-execution vulnerability in .NET Framework.

    Read update Source: Microsoft

    Build
    4.8.9344.0
    Security
    6 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 25H2 · Windows Server 2025 Security update
    Updated

    KB5120708

    Six runtime vulnerabilities addressed; WPF print failures later resolved

    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.

    Check the newer update, KB5126052

    Key changes 6 CVEs · 6 changes

    • Fix .NET Framework: Addresses an elevation-of-privilege vulnerability in .NET Framework.
    • Fix .NET Framework: Addresses an elevation-of-privilege vulnerability in .NET Framework.
    • Fix .NET Framework: Addresses a remote code execution vulnerability in .NET Framework.

    Read update Source: Microsoft

    Builds
    4.8.9344.0 · 2.0.50727.9183
    Security
    6 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 24H2 Security update
    Updated

    KB5120710

    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.

    Check the newer update, KB5126052

    Key changes 6 CVEs · 6 changes

    • Fix .NET Framework: Addresses an elevation-of-privilege vulnerability in .NET Framework.
    • Fix .NET Framework: Addresses an elevation-of-privilege vulnerability in .NET Framework.
    • Fix .NET Framework: Addresses a remote code execution vulnerability in .NET Framework.

    Read update Source: Microsoft

    Builds
    4.8.9343.0 · 2.0.50727.9183
    Security
    6 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 23H2 Security update
    Updated

    KB5120713

    Elevation-of-privilege and code-execution flaws addressed

    The update addresses six .NET Framework vulnerabilities, including remote-code-execution flaws. Two WPF printing problems associated with the August update were later resolved by September and October updates.

    Check the newer update, KB5126424

    Key changes 6 CVEs · 6 changes

    • Fix .NET Framework: An elevation-of-privilege vulnerability is addressed.
    • Fix .NET Framework: An elevation-of-privilege vulnerability is addressed.
    • Fix .NET Framework: A remote-code-execution vulnerability is addressed.

    Read update Source: Microsoft

    Builds
    4.8.9343.0 · 2.0.50727.9183
    Security
    6 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 21H2, 22H2 Security update
    Updated

    KB5120709

    Runtime vulnerabilities closed; WPF printing errors need later updates

    Closes six .NET Framework vulnerabilities, including three remote-code-execution flaws. Two WPF printing issues are resolved only in later updates.

    Check the newer update, KB5126421

    Key changes 6 CVEs · 6 changes

    • Fix .NET Framework: Closes an elevation-of-privilege vulnerability, CVE-2026-65810.
    • Fix .NET Framework: Closes an elevation-of-privilege vulnerability, CVE-2026-62872.
    • Fix .NET Framework: Closes a remote-code-execution vulnerability, CVE-2026-62886.

    Read update Source: Microsoft

    Builds
    4.8.9343.0 · 2.0.50727.9183
    Security
    6 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows Server 2022 Security update
    Updated

    KB5120714

    Six runtime vulnerabilities addressed; WPF printing may fail

    Addresses six .NET Framework vulnerabilities, including remote-code-execution flaws. Some WPF apps may fail when printing or generating PDF/XPS content; later cumulative updates resolve the two listed issues.

    Check the newer update, KB5126422

    Key changes 6 CVEs · 6 changes

    • Fix .NET Framework: A .NET Framework elevation-of-privilege vulnerability is addressed.
    • Fix .NET Framework: A .NET Framework elevation-of-privilege vulnerability is addressed.
    • Fix .NET Framework: A .NET Framework remote-code-execution vulnerability is addressed.

    Read update Source: Microsoft

    Builds
    4.8.9343.0 · 2.0.50727.9183
    Security
    6 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 26H1 Security update

    KB5101002

    Fixes hanging HTTP requests and debugger value reports

    Addresses 17 .NET Framework security vulnerabilities and fixes two reliability issues, including HTTP requests that could hang in certain secure connection scenarios.

    Check the newer update, KB5120711

    Key changes 17 CVEs · 2 changes

    • Fix .NET Libraries: Some synchronous web requests no longer hang in the specified secure connection scenarios.
    • Fix .NET Runtime: The Visual Studio x86 debugger reports certain floating-point values correctly while stepping through mixed-code applications.
    • CVSS 8.1 CVE-2026-47304: .NET Security Feature Bypass Vulnerability

    Read update Source: Microsoft

    Build
    4.8.9340.0
    Security
    17 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 25H2 · Windows Server 2025 Security update

    KB5100998

    Remote-code execution flaw among 17 vulnerabilities addressed

    Addresses 17 Important .NET vulnerabilities, including a remote-code execution flaw, and two reliability issues. None are rated Critical or known to be publicly disclosed or exploited.

    Check the newer update, KB5120708

    Key changes 17 CVEs · 19 changes

    • Fix .NET Framework: The update addresses a security flaw that could cause denial of service.
    • Fix .NET Framework: The update addresses a security feature bypass flaw.
    • Fix .NET Framework: The update addresses a security flaw that could cause denial of service.

    Read update Source: Microsoft

    Builds
    4.8.9340.0 · 2.0.50727.9182
    Security
    17 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 24H2 Security update

    KB5101001

    Runtime flaws addressed; secure requests and debugging improved

    The update addresses 17 important vulnerabilities. It also addresses hangs in some secure web requests and wrong values in Visual Studio debugging.

    Check the newer update, KB5120710

    Key changes 17 CVEs · 19 changes

    • Fix .NET Framework: A flaw could let someone disrupt a service.
    • Fix .NET Framework: A flaw could let someone get around a security feature.
    • Fix .NET Framework: A flaw could let someone disrupt a service.

    Read update Source: Microsoft

    Builds
    4.8.9339.0 · 2.0.50727.9182
    Security
    17 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 11 23H2 Security update

    KB5101004

    Remote code execution flaw addressed; secure request hangs improved

    The update addresses 17 Important vulnerabilities, including a remote code execution flaw, and two reliability issues involving hanging secure web requests and incorrect debugger reports.

    Check the newer update, KB5120713

    Key changes 17 CVEs · 2 changes

    • Fix .NET Libraries: The update addresses cases where secure web requests could hang with certain server configurations.
    • Fix .NET Runtime: The update addresses cases where certain floating-point values could be reported incorrectly while debugging.
    • CVSS 8.1 CVE-2026-47304: .NET Security Feature Bypass Vulnerability

    Read update Source: Microsoft

    Builds
    4.8.9339.0 · 2.0.50727.9182
    Security
    17 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows 10 21H2, 22H2 Security update

    KB5101000

    17 .NET flaws addressed; secure web requests and debugger improved

    The update addresses 17 important .NET Framework security flaws, including one that could let an attacker run code. It also addresses hanging secure web requests and incorrect debugger values.

    Check the newer update, KB5120709

    Key changes 17 CVEs · 19 changes

    • Fix .NET Framework: A flaw that could disrupt a service is addressed.
    • Fix .NET Framework: A flaw that could bypass a security check is addressed.
    • Fix .NET Framework: A flaw that could disrupt a service is addressed.

    Read update Source: Microsoft

    Builds
    4.8.9339.0 · 2.0.50727.9182
    Security
    17 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8.1 .NET Framework 3.5 / 4.8.1 for Windows Server 2022 Security update

    KB5101005

    Secure web requests and debugger value reports improved

    Addresses 17 .NET Framework vulnerabilities and two reliability issues. Some secure web requests could hang, and a debugger could report certain values incorrectly.

    Check the newer update, KB5120714

    Key changes 17 CVEs · 19 changes

    • Fix .NET Framework: Addresses a flaw that could make an app stop responding.
    • Fix .NET Framework: Addresses a flaw that could let an attacker get around a security check.
    • Fix .NET Framework: Addresses a flaw that could make an app stop responding.

    Read update Source: Microsoft

    Builds
    4.8.9339.0 · 2.0.50727.9182
    Security
    17 vulnerabilities fixed
    Restart
    Required