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.NET Framework 3.5

.NET Framework 3.5

Every published release for .NET Framework 3.5, newest first: what each update changes, whether to install it and any confirmed known issues.

Latest
KB5127694 Oct 13, 2026
File version
2.0.50727.9188
Released
Nov 19, 2007
All editions
updates until Jan 9, 2029
Known issues
1 open

Latest update

  • KB5127694 Released Oct 13, 2026
    File version 2.0.50727.9188

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 .NET Framework 3.5 / 4.8 for Windows 10 21H2, 22H2 Security update
    Updated

    KB5127683

    Critical .NET spoofing flaw addressed

    CVE-2026-96222 is a critical .NET Framework spoofing flaw addressed by this update. It also addresses the publicly disclosed security-feature bypass CVE-2026-108398.

    Key changes 21 CVEs · 20 changes

    • Fix .NET Framework: A .NET Framework denial-of-service flaw is addressed (CVE-2026-58280).
    • Fix .NET Framework: A .NET Framework elevation-of-privilege flaw is addressed (CVE-2026-69439).
    • Fix .NET Framework: A .NET Framework denial-of-service flaw is addressed (CVE-2026-69651).

    Read update Source: Microsoft

    Builds
    4.8.4811.0 · 2.0.50727.9188
    Security
    21 fixed · 1 critical
    Restart
    Required
  • .NET Framework 3.5 / 4.8 .NET Framework 3.5 / 4.8 for Windows Server 2022 Security update

    KB5127687

    Remote-code and security-bypass flaws are addressed

    Addresses .NET Framework security flaws, including risks that could let attackers run code or bypass a security feature. It covers Windows Server 2022 systems with .NET Framework 3.5 or 4.8 installed.

    Key changes 21 CVEs · 19 changes

    • Fix .NET Framework: A flaw that could let an attacker disrupt a service is addressed.
    • Fix .NET Framework: A flaw that could let an attacker gain higher permissions is addressed.
    • Fix .NET Framework: A flaw that could let an attacker disrupt a service is addressed.

    Read update Source: Microsoft

    Builds
    4.8.4811.0 · 2.0.50727.9188
    Security
    21 fixed · 1 critical
    Restart
    Required
  • .NET Framework 3.5 / 4.8 .NET Framework 3.5 / 4.8 for Windows 10 1809 · Windows Server 2019 Security update

    KB5127685

    Closes a critical spoofing flaw and a disclosed security bypass

    Fixes 21 security flaws, including a critical spoofing flaw and a publicly disclosed .NET Framework security bypass. It applies to Windows 10 version 1809 and Windows Server 2019.

    Key changes 21 CVEs · 19 changes

    • Improved .NET Framework: Blocks a flaw that could disrupt a service.
    • Improved .NET Framework: Blocks a flaw that could let someone gain higher access.
    • Improved .NET Framework: Blocks a flaw that could disrupt a service.

    Read update Source: Microsoft

    Builds
    4.8.4811.0 · 2.0.50727.9073
    Security
    21 fixed · 1 critical
    Restart
    Required
  • .NET Framework 3.5 / 4.7.2 .NET Framework 3.5 / 4.7.2 for Windows 10 1809 · Windows Server 2019 Security update

    KB5127666

    Publicly disclosed .NET security bypass addressed

    The update addresses 21 vulnerabilities, including one critical flaw. CVE-2026-108398 could bypass a .NET Framework security protection and was publicly disclosed.

    Key changes 21 CVEs · 19 changes

    • Fix .NET Framework: The update addresses a flaw that could make a service unavailable.
    • Fix .NET Framework: The update addresses a flaw that could let someone gain higher permissions.
    • Fix .NET Framework: The update addresses a flaw that could make a service unavailable.

    Read update Source: Microsoft

    Builds
    4.7.4150.0 · 2.0.50727.9073
    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 .NET Framework 3.5 / 4.8 for Windows 10 21H2, 22H2 Security update

    KB5126046

    Privilege and remote-code-execution flaws addressed

    Two .NET Framework flaws could allow higher privileges or remote code execution. The update addresses both; restart if affected files are in use.

    Check the newer update, KB5127683

    Key changes 2 CVEs · 2 changes

    • Fix .NET Framework: A flaw that could let someone gain higher privileges is addressed.
    • Fix .NET Framework: A flaw that could let someone run code remotely is addressed.
    • CVSS 8.8 CVE-2026-69522: .NET and Visual Studio Remote Code Execution Vulnerability

    Read update Source: Microsoft

    Builds
    4.8.4806.0 · 2.0.50727.9183
    Security
    2 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8 .NET Framework 3.5 / 4.8 for Windows Server 2022 Security update

    KB5126050

    Privilege-escalation and code-execution flaws addressed

    The update addresses .NET Framework elevation-of-privilege and remote-code-execution vulnerabilities. Although the KB page still lists CVE-2026-62886, a later correction removed it from the vulnerability listing.

    Check the newer update, KB5127687

    Key changes 2 CVEs · 2 changes

    • Fix .NET Framework: The elevation-of-privilege vulnerability CVE-2026-62886 is addressed, according to the KB page.
    • Fix .NET Framework: The remote code execution vulnerability CVE-2026-69522 is addressed.
    • CVSS 8.8 CVE-2026-69522: .NET and Visual Studio Remote Code Execution Vulnerability

    Read update Source: Microsoft

    Builds
    4.8.4806.0 · 2.0.50727.9183
    Security
    2 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.8 .NET Framework 3.5 / 4.8 for Windows 10 1809 · Windows Server 2019 Security update

    KB5126048

    Elevation-of-privilege and remote-code flaws addressed

    The update addresses two .NET Framework security vulnerabilities, including remote code execution and elevation of privilege. It applies to Windows 10 version 1809 and Windows Server 2019 systems with .NET Framework 3.5 or 4.8.

    Check the newer update, KB5127685

    Key changes 2 CVEs · 2 changes

    • Fix .NET Framework: Addresses an elevation-of-privilege vulnerability.
    • Fix .NET Framework: Addresses a remote code execution vulnerability.
    • CVSS 8.8 CVE-2026-69522: .NET and Visual Studio Remote Code Execution Vulnerability

    Read update Source: Microsoft

    Builds
    4.8.4806.0 · 2.0.50727.9070
    Security
    2 vulnerabilities fixed
    Restart
    Required
  • .NET Framework 3.5 / 4.7.2 .NET Framework 3.5 / 4.7.2 for Windows 10 1809 · Windows Server 2019 Security update

    KB5126043

    Privilege and code-execution flaws addressed

    The update addresses two security flaws: one could let an attacker gain higher privileges, and another could let them run code.

    Check the newer update, KB5127666

    Key changes 2 CVEs · 2 changes

    • 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.
    • CVSS 8.8 CVE-2026-69522: .NET and Visual Studio Remote Code Execution Vulnerability

    Read update Source: Microsoft

    Builds
    4.7.4145.0 · 2.0.50727.9070
    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