October 14, 2025-Security and Quality Rollup for .NET Framework 3.5 for Windows Server 2012 (KB5066148)

Applies To
.NET

Note

  • Applies to:
  • Microsoft .NET Framework 3.5
Important The installation of this Extended Security Update (ESU) might fail when you try to install it on an Azure Arc-enabled device that is running Windows Server 2012. For a successful installation, please make sure all Subset of endpoints for ESU only are met as described in Connected Machine agent network requirements.

End of support information

Note

  • Windows Server 2012 reached the end of support (EOS) on October 10, 2023. Extended Security Updates (ESUs) are available for purchase and will continue for three years, renewable on an annual basis, until the final date on October 13, 2026. For more information, see Windows Server End of Support: Key Dates. For information about the procedure to continue receiving security updates, see KB5031043. For more information about the ESU program, see Learn about the ESU program.

                        We recommend that you upgrade to a later version of Windows Server. For more information, see Overview of Windows Server upgrades.

  • Windows Embedded 8 Standard reached the end of support (EOS) on July 11, 2023. Therefore, technical assistance and software updates are no longer provided.

Summary

The October 14, 2025 update for Windows Server 2012 includes cumulative security and reliability improvements in .NET Framework 3.5.

Note

Note Verify that you have installed the required updates listed in the How to get this update section before installing this update.

Security Improvements

CVE-2025-55248 - .NET Framework Information Disclosure vulnerability
              This security update addresses an information disclosure vulnerability detailed in CVE-2025-55248.

Quality and Reliability Improvements

There are no new Quality and Reliability Improvements in this update.

Additional information about this update

The following articles contain additional information about this update as it relates to individual product versions.

  • 5066740 Description of the Security and Quality Rollup for .NET Framework 3.5, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 for Windows Server 2012 (KB5066740)

Known issues in this update

Microsoft is not currently aware of any issues in this update.

How to get this update

Before installing this update

We strongly recommend that you install the latest servicing stack update (SSU) for your operating system before installing the latest Rollup. SSUs improve the reliability of the update process to mitigate potential issues while installing the Rollup and applying Microsoft security fixes. For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

If you use Windows Update, the latest SSU (KB5044413) will be offered to you automatically. To get the standalone package for the latest SSU, search for it in the Microsoft Update Catalog.

Language packs

If you install a language pack after you install this update, you must reinstall this update. Therefore, we recommend that you install any language packs that you need before you install this update. For more information, see Add language packs to Windows.

To apply this update, you must have .NET Framework 3.5 installed.

Install this update

Release Channel Available Next Step
Windows Update and Microsoft Update Yes None. This update will be downloaded and installed automatically from Windows Update.
Microsoft Update Catalog Yes To get the standalone package for this update, go to the Microsoft Update Catalog website.
Windows Server Update Services (WSUS) Yes This individual .NET Framework product update will be installed, as applicable, by applying the operating system update. For more information about operating system updates see additional information about this update section.

Restart requirement

You may need to restart the computer after you apply this update if any affected files are being used. We recommend that you exit all .NET Framework-based applications before you apply this update.

Update deployment information

For deployment details for this security update, see the Deployments tab of the Microsoft Security Response Center (MSRC) Security Update Guide.

Update replacement information

This update replaces previously released updates KB5050184 and KB5065959.

File Information

File hash information

File name SHA256 hash
windows8-rt-kb5066148-x64.msu CFAC53581ED8C0BA5BBFC488F40B7CDF5EB91E11BFE440C50004DCBAE2C23858

For all supported x64-based versions

File name File version File size Date Time Platform SP requirement Service branch
Aspnet_regbrowsers.exe 2.0.50727.8977 13,312 13-Jun-2024 20:40 x64 SPN AMD64_ASP
Aspnet_regsql.exe 2.0.50727.8977 102,400 13-Jun-2024 20:40 x64 SPN AMD64_ASP
Big5.nlp Not applicable 66,728 09-Jul-2024 03:18 Not applicable None Not applicable
Bopomofo.nlp Not applicable 82,172 09-Jul-2024 03:18 Not applicable None Not applicable
Ksc.nlp Not applicable 116,756 09-Jul-2024 03:18 Not applicable None Not applicable
Mscorlib.dll 2.0.50727.8980 4,644,864 18-Jul-2024 01:03 x64 None Not applicable
Normidna.nlp Not applicable 59,342 09-Jul-2024 03:18 Not applicable None Not applicable
Normnfc.nlp Not applicable 45,794 09-Jul-2024 03:18 Not applicable None Not applicable
Normnfd.nlp Not applicable 39,284 09-Jul-2024 03:18 Not applicable None Not applicable
Normnfkc.nlp Not applicable 66,384 09-Jul-2024 03:18 Not applicable None Not applicable
Normnfkd.nlp Not applicable 60,294 09-Jul-2024 03:18 Not applicable None Not applicable
Prc.nlp Not applicable 83,748 09-Jul-2024 03:18 Not applicable None Not applicable
Prcp.nlp Not applicable 83,748 09-Jul-2024 03:18 Not applicable None Not applicable
Sortkey.nlp Not applicable 262,148 09-Jul-2024 03:18 Not applicable None Not applicable
Sorttbls.nlp Not applicable 20,320 09-Jul-2024 03:18 Not applicable None Not applicable
Xjis.nlp Not applicable 28,288 09-Jul-2024 03:18 Not applicable None Not applicable
Aspnet_regiis.exe 2.0.50727.8977 49,104 13-Jun-2024 20:40 x64 SPN AMD64_NETFX-ASP
Aspnet_wp.exe 2.0.50727.8975 46,520 04-Oct-2023 00:24 x64 SPN AMD64_NETFX-ASP
Mscordacwks.dll 2.0.50727.8980 1,760,704 18-Jul-2024 01:03 x64 None Not applicable
Mscorjit.dll 2.0.50727.8977 1,577,904 13-Jun-2024 20:40 x64 None Not applicable
Mscorpe.dll 2.0.50727.8977 169,904 13-Jun-2024 20:40 x64 None Not applicable
Mscorsvc.dll 2.0.50727.8793 495,232 24-Jul-2018 15:10 x64 None Not applicable
Mscorwks.dll 2.0.50727.8980 10,627,008 18-Jul-2024 01:03 x64 None Not applicable
Peverify.dll 2.0.50727.8977 212,400 13-Jun-2024 20:40 x64 None Not applicable
Sos.dll 2.0.50727.8980 489,392 18-Jul-2024 01:03 x64 None Not applicable
System.configuration.dll 2.0.50727.8953 430,080 03-Sep-2020 13:17 x86 None Not applicable
System.data.sqlxml.dll 2.0.50727.8773 745,472 01-Dec-2017 13:13 x86 None Not applicable
System.directoryservices.dll 2.0.50727.8964 401,408 05-Apr-2022 00:12 x86 None Not applicable
System.management.dll 2.0.50727.8766 389,120 12-Jul-2017 13:09 x86 None Not applicable
System.runtime.remoting.dll 2.0.50727.8976 307,200 06-Dec-2023 01:18 x86 None Not applicable
System.security.dll 2.0.50727.8953 274,432 03-Sep-2020 13:17 x86 None Not applicable
System.web.regularexpressions.dll 2.0.50727.8975 98,304 04-Oct-2023 00:24 x86 None Not applicable
System.xml.dll 2.0.50727.8773 2,056,192 01-Dec-2017 13:13 x86 None Not applicable
System.dll 2.0.50727.8981 3,215,360 11-Sep-2025 01:42 x86 None Not applicable
Vbc.exe 8.0.50727.8977 1,806,816 13-Jun-2024 20:40 x64 None Not applicable
Vbc.rsp Not applicable 1,070 13-Jun-2024 20:40 Not applicable None Not applicable
Webengine.dll 2.0.50727.8975 750,112 04-Oct-2023 00:24 x64 None Not applicable
Wminet_utils.dll 2.0.50727.8766 140,960 12-Jul-2017 13:09 x64 None Not applicable
System.web.extensions.dll 3.5.30729.8966 1,282,048 06-Mar-2024 01:19 x86 None Not applicable
Vbc.exe 9.0.30729.8971 2,365,008 13-Jun-2024 20:41 x64 None Not applicable
Vbc.rsp Not applicable 1,489 30-Dec-2023 00:50 Not applicable None Not applicable
Vbc7ui.dll 9.0.30729.6400 231,512 13-Jun-2024 20:41 x64 None Not applicable
Presentationcore.dll 3.0.6920.8971 4,006,400 16-Aug-2024 00:18 x64 None Not applicable
Presentationfontcache.exe.config Not applicable 161 16-Aug-2024 00:18 Not applicable None Not applicable
Wpfgfx_v0300.dll 3.0.6920.8971 2,259,376 16-Aug-2024 00:18 x64 None Not applicable
System.data.dll 2.0.50727.8976 3,158,528 06-Dec-2023 01:18 x64 None Not applicable
System.printing.dll 3.0.6920.8971 358,400 16-Aug-2024 00:18 x64 None Not applicable
System.web.dll 2.0.50727.8975 5,300,224 04-Oct-2023 00:24 x64 None Not applicable
Servicemonikersupport.dll 3.0.4506.8841 30,192 27-Mar-2020 13:11 x64 None Not applicable
Smdiagnostics.dll 3.0.4506.8841 94,208 27-Mar-2020 13:11 x86 None Not applicable
Smsvchost.exe 3.0.4506.8841 127,488 27-Mar-2020 13:11 x86 None Not applicable
System.identitymodel.dll 3.0.4506.8841 405,504 27-Mar-2020 13:11 x86 None Not applicable
System.runtime.serialization.dll 3.0.4506.8841 847,872 27-Mar-2020 13:11 x86 None Not applicable
System.runtime.serialization.dll 3.0.4506.8841 847,872 27-Mar-2020 13:11 x86 None Not applicable
System.servicemodel.dll 3.0.4506.8841 5,337,088 27-Mar-2020 13:11 x86 None Not applicable
System.servicemodel.washosting.dll 3.0.4506.8841 32,768 27-Mar-2020 13:11 x86 None Not applicable
System.servicemodel.dll 3.0.4506.8841 5,337,088 27-Mar-2020 13:11 x86 None Not applicable
Penimc.dll 3.0.6920.8971 89,008 16-Aug-2024 00:18 x64 None Not applicable
Presentationframework.dll 3.0.6920.8971 4,653,056 16-Aug-2024 00:18 x86 None Not applicable
Presentationhostdll.dll 3.0.6920.8971 175,648 16-Aug-2024 00:18 x64 None Not applicable
Reachframework.dll 3.0.6920.8971 536,576 16-Aug-2024 00:18 x86 None Not applicable
Windowsbase.dll 3.0.6920.8971 1,118,208 16-Aug-2024 00:18 x86 None Not applicable
System.workflow.activities.dll 3.0.4203.8833 1,060,864 07-Dec-2019 02:06 x86 None Not applicable
System.workflow.componentmodel.dll 3.0.4203.8833 1,531,904 07-Dec-2019 02:06 x86 None Not applicable
System.workflow.runtime.dll 3.0.4203.8833 454,656 07-Dec-2019 02:06 x86 None Not applicable
Presentationframework.dll 3.0.6920.8971 5,296,128 16-Aug-2024 00:17 x86 None Not applicable
Reachframework.dll 3.0.6920.8971 536,576 16-Aug-2024 00:17 x86 None Not applicable
Smdiagnostics.dll 3.0.4506.8841 110,592 27-Mar-2020 13:11 x86 None Not applicable
Smsvchost.exe 3.0.4506.8841 139,568 27-Mar-2020 13:11 x86 None Not applicable
System.configuration.dll 2.0.50727.8953 430,080 03-Sep-2020 13:16 x86 None Not applicable
System.data.sqlxml.dll 2.0.50727.8773 745,472 01-Dec-2017 13:05 x86 None Not applicable
System.directoryservices.dll 2.0.50727.8964 401,408 05-Apr-2022 00:12 x86 None Not applicable
System.identitymodel.dll 3.0.4506.8841 446,464 27-Mar-2020 13:11 x86 None Not applicable
System.management.dll 2.0.50727.8766 389,120 12-Jul-2017 13:09 x86 None Not applicable
System.resources.dll 2.0.50727.4927 237,568 25-Aug-2025 00:18 x86 None Not applicable
System.resources.dll 2.0.50727.4927 200,704 25-Aug-2025 00:18 x86 None Not applicable
System.resources.dll 2.0.50727.4927 196,608 25-Aug-2025 00:18 x86 None Not applicable
System.resources.dll 2.0.50727.6400 212,992 25-Aug-2025 00:18 x86 None Not applicable
System.resources.dll 2.0.50727.4927 290,816 25-Aug-2025 00:18 x86 None Not applicable
System.resources.dll 2.0.50727.6400 208,896 09-Sep-2025 02:54 x86 None Not applicable
System.resources.dll 2.0.50727.4927 196,608 09-Sep-2025 02:54 x86 None Not applicable
System.resources.dll 2.0.50727.6400 212,992 25-Aug-2025 00:18 x86 None Not applicable
System.resources.dll 2.0.50727.4927 217,088 09-Sep-2025 02:54 x86 None Not applicable
System.resources.dll 2.0.50727.4927 212,992 09-Sep-2025 02:54 x86 None Not applicable
System.resources.dll 2.0.50727.6400 204,800 09-Sep-2025 02:58 x86 None Not applicable
System.resources.dll 2.0.50727.6400 233,472 09-Sep-2025 02:58 x86 None Not applicable
System.resources.dll 2.0.50727.6400 217,088 09-Sep-2025 02:58 x86 None Not applicable
System.resources.dll 2.0.50727.4927 192,512 09-Sep-2025 02:58 x86 None Not applicable
System.resources.dll 2.0.50727.6400 208,896 09-Sep-2025 02:58 x86 None Not applicable
System.resources.dll 2.0.50727.4927 204,800 09-Sep-2025 02:58 x86 None Not applicable
System.resources.dll 2.0.50727.4927 204,800 09-Sep-2025 02:58 x86 None Not applicable
System.resources.dll 2.0.50727.4927 204,800 09-Sep-2025 02:58 x86 None Not applicable
System.resources.dll 2.0.50727.4927 262,144 09-Sep-2025 02:55 x86 None Not applicable
System.resources.dll 2.0.50727.4927 196,608 09-Sep-2025 02:55 x86 None Not applicable
System.resources.dll 2.0.50727.4927 196,608 09-Sep-2025 02:55 x86 None Not applicable
System.resources.dll 2.0.50727.6400 184,320 09-Sep-2025 02:55 x86 None Not applicable
System.resources.dll 2.0.50727.6400 184,320 25-Aug-2025 00:18 x86 None Not applicable
System.runtime.remoting.dll 2.0.50727.8976 307,200 06-Dec-2023 01:18 x86 None Not applicable
System.runtime.serialization.dll 3.0.4506.8841 970,752 27-Mar-2020 13:11 x86 None Not applicable
System.runtime.serialization.dll 3.0.4506.8841 970,752 27-Mar-2020 13:11 x86 None Not applicable
System.security.dll 2.0.50727.8953 274,432 03-Sep-2020 13:16 x86 None Not applicable
System.servicemodel.dll 3.0.4506.8841 5,996,544 27-Mar-2020 13:11 x86 None Not applicable
System.servicemodel.washosting.dll 3.0.4506.8841 32,768 27-Mar-2020 13:11 x86 None Not applicable
System.servicemodel.dll 3.0.4506.8841 5,996,544 27-Mar-2020 13:11 x86 None Not applicable
System.web.extensions.dll 3.5.30729.8966 1,282,048 06-Mar-2024 01:19 x86 None Not applicable
System.web.regularexpressions.dll 2.0.50727.8975 98,304 04-Oct-2023 00:23 x86 None Not applicable
System.workflow.activities.dll 3.0.4203.8833 1,142,784 07-Dec-2019 02:06 x86 None Not applicable
System.workflow.componentmodel.dll 3.0.4203.8833 1,638,400 07-Dec-2019 02:06 x86 None Not applicable
System.workflow.runtime.dll 3.0.4203.8833 540,672 07-Dec-2019 02:06 x86 None Not applicable
System.xml.dll 2.0.50727.8773 2,056,192 01-Dec-2017 13:05 x86 None Not applicable
System.dll 2.0.50727.8981 3,215,360 11-Sep-2025 01:39 x86 None Not applicable
Windowsbase.dll 3.0.6920.8971 1,257,472 16-Aug-2024 00:17 x86 None Not applicable
Aspnet_regbrowsers.exe 2.0.50727.8977 24,576 11-Jun-2024 01:29 x86 SPN X86_ASP
Aspnet_regsql.exe 2.0.50727.8977 106,496 11-Jun-2024 01:29 x86 SPN X86_ASP
Big5.nlp Not applicable 66,728 09-Jul-2024 03:18 Not applicable None Not applicable
Bopomofo.nlp Not applicable 82,172 09-Jul-2024 03:18 Not applicable None Not applicable
Ksc.nlp Not applicable 116,756 09-Jul-2024 03:18 Not applicable None Not applicable
Mscorlib.dll 2.0.50727.8980 4,628,480 18-Jul-2024 01:03 x86 None Not applicable
Normidna.nlp Not applicable 59,342 09-Jul-2024 03:18 Not applicable None Not applicable
Normnfc.nlp Not applicable 45,794 09-Jul-2024 03:18 Not applicable None Not applicable
Normnfd.nlp Not applicable 39,284 09-Jul-2024 03:18 Not applicable None Not applicable
Normnfkc.nlp Not applicable 66,384 09-Jul-2024 03:18 Not applicable None Not applicable
Normnfkd.nlp Not applicable 60,294 09-Jul-2024 03:18 Not applicable None Not applicable
Prc.nlp Not applicable 83,748 09-Jul-2024 03:18 Not applicable None Not applicable
Prcp.nlp Not applicable 83,748 09-Jul-2024 03:18 Not applicable None Not applicable
Sortkey.nlp Not applicable 262,148 09-Jul-2024 03:18 Not applicable None Not applicable
Sorttbls.nlp Not applicable 20,320 09-Jul-2024 03:18 Not applicable None Not applicable
Xjis.nlp Not applicable 28,288 09-Jul-2024 03:18 Not applicable None Not applicable
Aspnet_regiis.exe 2.0.50727.8977 34,360 11-Jun-2024 01:29 x86 SPN X86_NETFX-ASP
Aspnet_wp.exe 2.0.50727.8975 34,760 04-Oct-2023 00:23 x86 SPN X86_NETFX-ASP
Mscordacwks.dll 2.0.50727.8980 993,720 18-Jul-2024 01:03 x86 None Not applicable
Mscorjit.dll 2.0.50727.8977 368,064 11-Jun-2024 01:29 x86 None Not applicable
Mscorpe.dll 2.0.50727.8977 115,136 11-Jun-2024 01:29 x86 None Not applicable
Mscorsvc.dll 2.0.50727.8793 231,992 24-Jul-2018 15:10 x86 None Not applicable
Mscorwks.dll 2.0.50727.8980 6,414,256 18-Jul-2024 01:03 x86 None Not applicable
Peverify.dll 2.0.50727.8977 145,440 11-Jun-2024 01:29 x86 None Not applicable
Sos.dll 2.0.50727.8980 393,264 18-Jul-2024 01:03 x86 None Not applicable
Vbc.exe 8.0.50727.8977 1,175,136 11-Jun-2024 01:29 x86 None Not applicable
Vbc.rsp Not applicable 1,070 11-Jun-2024 01:29 Not applicable None Not applicable
Webengine.dll 2.0.50727.8975 440,872 04-Oct-2023 00:23 x86 None Not applicable
Wminet_utils.dll 2.0.50727.8766 116,896 12-Jul-2017 13:09 x86 None Not applicable
System.web.extensions.dll 3.5.30729.8966 1,282,048 06-Mar-2024 01:19 x86 None Not applicable
Vbc.exe 9.0.30729.8971 1,722,848 13-Jun-2024 20:40 x86 None Not applicable
Vbc.rsp Not applicable 1,489 30-Dec-2023 00:51 Not applicable None Not applicable
Vbc7ui.dll 9.0.30729.6400 231,512 11-Jun-2024 01:29 x86 None Not applicable
Presentationcore.dll 3.0.6920.8971 4,222,976 16-Aug-2024 00:17 x86 None Not applicable
Presentationfontcache.exe.config Not applicable 161 16-Aug-2024 00:17 Not applicable None Not applicable
Wpfgfx_v0300.dll 3.0.6920.8971 1,741,248 16-Aug-2024 00:17 x86 None Not applicable
System.data.dll 2.0.50727.8976 2,983,936 06-Dec-2023 01:17 x86 None Not applicable
System.printing.dll 3.0.6920.8971 372,736 16-Aug-2024 00:17 x86 None Not applicable
System.web.dll 2.0.50727.8975 5,292,032 04-Oct-2023 00:23 x86 None Not applicable
Servicemonikersupport.dll 3.0.4506.8841 28,152 27-Mar-2020 13:11 x86 None Not applicable
System.identitymodel.dll 3.0.4506.8841 446,464 27-Mar-2020 13:11 x86 None Not applicable
System.runtime.serialization.dll 3.0.4506.8841 970,752 27-Mar-2020 13:11 x86 None Not applicable
System.servicemodel.dll 3.0.4506.8841 5,996,544 27-Mar-2020 13:11 x86 None Not applicable
Penimc.dll 3.0.6920.8971 72,112 16-Aug-2024 00:17 x86 None Not applicable
Presentationframework.dll 3.0.6920.8971 5,296,128 16-Aug-2024 00:17 x86 None Not applicable
Presentationhostdll.dll 3.0.6920.8971 134,688 16-Aug-2024 00:17 x86 None Not applicable
Reachframework.dll 3.0.6920.8971 536,576 16-Aug-2024 00:17 x86 None Not applicable
Windowsbase.dll 3.0.6920.8971 1,257,472 16-Aug-2024 00:17 x86 None Not applicable
System.workflow.activities.dll 3.0.4203.8833 1,142,784 07-Dec-2019 02:06 x86 None Not applicable
System.workflow.componentmodel.dll 3.0.4203.8833 1,638,400 07-Dec-2019 02:06 x86 None Not applicable
System.workflow.runtime.dll 3.0.4203.8833 540,672 07-Dec-2019 02:06 x86 None Not applicable

How to obtain help and support for this update