Applies to:

Microsoft .NET Framework 3.5

Summary

A denial of service vulnerability exists when .NET Framework improperly handles web requests. An attacker who successfully exploited this vulnerability could cause a denial of service against a .NET Framework web application. The vulnerability can be exploited remotely, without authentication. A remote unauthenticated attacker could exploit this vulnerability by issuing specially crafted requests to the .NET Framework application. The update addresses the vulnerability by correcting how the .NET Framework web application handles web requests.

To learn more about the vulnerabilities, go to the following Common Vulnerabilities and Exposures (CVE).

Important

  • As a reminder to advanced IT administrators, updates to .NET Framework 3.5 for Windows 8.1 and Windows Server 2012 R2 should only be applied on systems where .NET Framework 3.5 is present and enabled. Customers who attempt to pre-install updates to .NET Framework 3.5 to offline images that do not contain the .NET Framework 3.5 product enabled will expose these systems to failures to enable .NET Framework 3.5 after the systems are online. For more extensive information about deploying .NET Framework 3.5, see Microsoft .NET Framework 3.5 Deployment Considerations.

  • All updates for Windows 8.1, Windows RT 8.1, and Windows Server 2012 R2 require that update KB 2919355 is installed. We recommend that you install update KB 2919355 on your Windows 8.1-based, Windows RT 8.1-based, or Windows Server 2012 R2-based computer so that you receive updates in the future.

  • 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.

Additional information about this update

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

  • 4556405 Description of the Security Only Update for .NET Framework 3.5, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 for Windows 8.1 and Windows Server 2012 R2 (KB4556405)

How to obtain and install the update

Method 1: Microsoft Update Catalog

To get the standalone package for this update, go to the Microsoft Update Catalog website.

Method 2: Windows Software Update Services (WSUS)

On your WSUS server, follow these steps:

  1. Select Start, select Administrative Tools, and then select Microsoft Windows Server Update Services 3.0.

  2. Expand ComputerName, and then select Action.

  3. Select Import Updates.

  4. WSUS opens a browser window in which you may be prompted to install an ActiveX control. You must install the ActiveX control to continue.

  5. After the ActiveX control is installed, you see the Microsoft Update Catalog screen. Type 4556405 into the Search box, and then select Search.

  6. Locate the .NET Framework packages that match the operating systems, languages, and processors in your environment. Select Add to add them to your basket.

  7. After you select all the packages that you require, select View Basket.

  8. To import the packages to your WSUS server, select Import.

  9. After the packages are imported, select Close to return to WSUS.

The updates are now available for installation through WSUS.

Prerequisites

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

Restart requirement

You must 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, go to the following article in the Microsoft Knowledge Base:

20200512 Security update deployment information: May 12, 2020

Update removal information

Note We do not recommend that you remove any security update. To remove this update, use the Programs and Features item in Control Panel.

Update restart information

This update does not require a system restart after you apply it unless files that are being updated are locked or are being used.


File information
The English (United States) version of this software update installs files that have the attributes that are listed in the following tables.

Windows 8.1 and Windows Server 2012 R2 file information

Note: The MANIFEST files (.manifest) and MUM files (.mum) that are installed are not listed.

File information

File hash information

File name

SHA1 hash

SHA256 hash

Windows8.1-KB4552966-x64.msu

E2072FB3AC9278D6CC9CCA0454D94D1A605645D2

364E909592C5CECC02048192F905A3A6EFDC98AD9BC04D4D33B889480DBEA6A7

Windows8.1-KB4552966-x64_New59.msu

E2072FB3AC9278D6CC9CCA0454D94D1A605645D2

364E909592C5CECC02048192F905A3A6EFDC98AD9BC04D4D33B889480DBEA6A7

Windows8.1-KB4552966-x86.msu

D55CE08903E46C6ED7F76D092E442983CC73CB64

EF75A54486D803D987A6EBBECB15CF766CF7A74885D468C8E3D13B0916BADE73

Windows8.1-KB4552966-x86_New83.msu

D55CE08903E46C6ED7F76D092E442983CC73CB64

EF75A54486D803D987A6EBBECB15CF766CF7A74885D468C8E3D13B0916BADE73

For all supported x64-based versions

File name

File version

File size

Date

Time

Platform

Big5.nlp

Not applicable

66,728

23-Jun-2019

22:15

Not applicable

Bopomofo.nlp

Not applicable

82,172

23-Jun-2019

22:15

Not applicable

Ksc.nlp

Not applicable

116,756

23-Jun-2019

22:15

Not applicable

Mscorlib.dll

2.0.50727.8813

4,575,232

28-Mar-2020

14:00

x64

Normidna.nlp

Not applicable

59,342

23-Jun-2019

22:15

Not applicable

Normnfc.nlp

Not applicable

45,794

23-Jun-2019

22:15

Not applicable

Normnfd.nlp

Not applicable

39,284

23-Jun-2019

22:15

Not applicable

Normnfkc.nlp

Not applicable

66,384

23-Jun-2019

22:15

Not applicable

Normnfkd.nlp

Not applicable

60,294

23-Jun-2019

22:15

Not applicable

Prc.nlp

Not applicable

83,748

23-Jun-2019

22:15

Not applicable

Prcp.nlp

Not applicable

83,748

23-Jun-2019

22:15

Not applicable

Sortkey.nlp

Not applicable

262,148

23-Jun-2019

22:15

Not applicable

Sorttbls.nlp

Not applicable

20,320

23-Jun-2019

22:15

Not applicable

Xjis.nlp

Not applicable

28,288

23-Jun-2019

22:15

Not applicable

Mscordacwks.dll

2.0.50727.8813

1,758,088

28-Mar-2020

14:00

x64

Mscorwks.dll

2.0.50727.8813

10,011,528

28-Mar-2020

14:00

x64

Sos.dll

2.0.50727.8813

486,792

28-Mar-2020

14:00

x64

Servicemonikersupport.dll

3.0.4506.8841

30,192

28-Mar-2020

14:00

x64

Smdiagnostics.dll

3.0.4506.8841

94,208

28-Mar-2020

14:00

x86

Smsvchost.exe

3.0.4506.8841

127,488

28-Mar-2020

14:00

x86

System.identitymodel.dll

3.0.4506.8841

405,504

28-Mar-2020

14:00

x86

System.runtime.serialization.dll

3.0.4506.8841

847,872

28-Mar-2020

14:00

x86

System.runtime.serialization.dll

3.0.4506.8841

847,872

28-Mar-2020

14:00

x86

System.servicemodel.dll

3.0.4506.8841

5,337,088

28-Mar-2020

14:00

x86

System.servicemodel.washosting.dll

3.0.4506.8841

32,768

28-Mar-2020

14:00

x86

System.servicemodel.dll

3.0.4506.8841

5,337,088

28-Mar-2020

14:00

x86

Smdiagnostics.dll

3.0.4506.8841

110,592

28-Mar-2020

13:37

x86

Smsvchost.exe

3.0.4506.8841

139,568

28-Mar-2020

13:37

x86

System.identitymodel.dll

3.0.4506.8841

446,464

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

System.servicemodel.washosting.dll

3.0.4506.8841

32,768

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

Big5.nlp

Not applicable

66,728

27-Oct-2017

23:27

Not applicable

Bopomofo.nlp

Not applicable

82,172

27-Oct-2017

23:27

Not applicable

Ksc.nlp

Not applicable

116,756

27-Oct-2017

23:27

Not applicable

Mscorlib.dll

2.0.50727.8813

4,558,848

28-Mar-2020

13:35

x86

Normidna.nlp

Not applicable

59,342

27-Oct-2017

23:27

Not applicable

Normnfc.nlp

Not applicable

45,794

27-Oct-2017

23:27

Not applicable

Normnfd.nlp

Not applicable

39,284

27-Oct-2017

23:27

Not applicable

Normnfkc.nlp

Not applicable

66,384

27-Oct-2017

23:27

Not applicable

Normnfkd.nlp

Not applicable

60,294

27-Oct-2017

23:27

Not applicable

Prc.nlp

Not applicable

83,748

27-Oct-2017

23:27

Not applicable

Prcp.nlp

Not applicable

83,748

27-Oct-2017

23:27

Not applicable

Sortkey.nlp

Not applicable

262,148

27-Oct-2017

23:27

Not applicable

Sorttbls.nlp

Not applicable

20,320

27-Oct-2017

23:27

Not applicable

Xjis.nlp

Not applicable

28,288

27-Oct-2017

23:27

Not applicable

Mscordacwks.dll

2.0.50727.8813

991,112

28-Mar-2020

13:35

x86

Mscorwks.dll

2.0.50727.8813

5,949,832

28-Mar-2020

13:35

x86

Sos.dll

2.0.50727.8813

390,536

28-Mar-2020

13:35

x86

Servicemonikersupport.dll

3.0.4506.8841

28,152

28-Mar-2020

13:37

x86

System.identitymodel.dll

3.0.4506.8841

446,464

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

For all supported x64-based versions

File name

File version

File size

Date

Time

Platform

Big5.nlp

Not applicable

66,728

23-Jun-2019

22:15

Not applicable

Bopomofo.nlp

Not applicable

82,172

23-Jun-2019

22:15

Not applicable

Ksc.nlp

Not applicable

116,756

23-Jun-2019

22:15

Not applicable

Mscorlib.dll

2.0.50727.8813

4,575,232

28-Mar-2020

14:00

x64

Normidna.nlp

Not applicable

59,342

23-Jun-2019

22:15

Not applicable

Normnfc.nlp

Not applicable

45,794

23-Jun-2019

22:15

Not applicable

Normnfd.nlp

Not applicable

39,284

23-Jun-2019

22:15

Not applicable

Normnfkc.nlp

Not applicable

66,384

23-Jun-2019

22:15

Not applicable

Normnfkd.nlp

Not applicable

60,294

23-Jun-2019

22:15

Not applicable

Prc.nlp

Not applicable

83,748

23-Jun-2019

22:15

Not applicable

Prcp.nlp

Not applicable

83,748

23-Jun-2019

22:15

Not applicable

Sortkey.nlp

Not applicable

262,148

23-Jun-2019

22:15

Not applicable

Sorttbls.nlp

Not applicable

20,320

23-Jun-2019

22:15

Not applicable

Xjis.nlp

Not applicable

28,288

23-Jun-2019

22:15

Not applicable

Mscordacwks.dll

2.0.50727.8813

1,758,088

28-Mar-2020

14:00

x64

Mscorwks.dll

2.0.50727.8813

10,011,528

28-Mar-2020

14:00

x64

Sos.dll

2.0.50727.8813

486,792

28-Mar-2020

14:00

x64

Servicemonikersupport.dll

3.0.4506.8841

30,192

28-Mar-2020

14:00

x64

Smdiagnostics.dll

3.0.4506.8841

94,208

28-Mar-2020

14:00

x86

Smsvchost.exe

3.0.4506.8841

127,488

28-Mar-2020

14:00

x86

System.identitymodel.dll

3.0.4506.8841

405,504

28-Mar-2020

14:00

x86

System.runtime.serialization.dll

3.0.4506.8841

847,872

28-Mar-2020

14:00

x86

System.runtime.serialization.dll

3.0.4506.8841

847,872

28-Mar-2020

14:00

x86

System.servicemodel.dll

3.0.4506.8841

5,337,088

28-Mar-2020

14:00

x86

System.servicemodel.washosting.dll

3.0.4506.8841

32,768

28-Mar-2020

14:00

x86

System.servicemodel.dll

3.0.4506.8841

5,337,088

28-Mar-2020

14:00

x86

Smdiagnostics.dll

3.0.4506.8841

110,592

28-Mar-2020

13:37

x86

Smsvchost.exe

3.0.4506.8841

139,568

28-Mar-2020

13:37

x86

System.identitymodel.dll

3.0.4506.8841

446,464

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

System.servicemodel.washosting.dll

3.0.4506.8841

32,768

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

Big5.nlp

Not applicable

66,728

27-Oct-2017

23:27

Not applicable

Bopomofo.nlp

Not applicable

82,172

27-Oct-2017

23:27

Not applicable

Ksc.nlp

Not applicable

116,756

27-Oct-2017

23:27

Not applicable

Mscorlib.dll

2.0.50727.8813

4,558,848

28-Mar-2020

13:35

x86

Normidna.nlp

Not applicable

59,342

27-Oct-2017

23:27

Not applicable

Normnfc.nlp

Not applicable

45,794

27-Oct-2017

23:27

Not applicable

Normnfd.nlp

Not applicable

39,284

27-Oct-2017

23:27

Not applicable

Normnfkc.nlp

Not applicable

66,384

27-Oct-2017

23:27

Not applicable

Normnfkd.nlp

Not applicable

60,294

27-Oct-2017

23:27

Not applicable

Prc.nlp

Not applicable

83,748

27-Oct-2017

23:27

Not applicable

Prcp.nlp

Not applicable

83,748

27-Oct-2017

23:27

Not applicable

Sortkey.nlp

Not applicable

262,148

27-Oct-2017

23:27

Not applicable

Sorttbls.nlp

Not applicable

20,320

27-Oct-2017

23:27

Not applicable

Xjis.nlp

Not applicable

28,288

27-Oct-2017

23:27

Not applicable

Mscordacwks.dll

2.0.50727.8813

991,112

28-Mar-2020

13:35

x86

Mscorwks.dll

2.0.50727.8813

5,949,832

28-Mar-2020

13:35

x86

Sos.dll

2.0.50727.8813

390,536

28-Mar-2020

13:35

x86

Servicemonikersupport.dll

3.0.4506.8841

28,152

28-Mar-2020

13:37

x86

System.identitymodel.dll

3.0.4506.8841

446,464

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

For all supported x86-based versions

File name

File version

File size

Date

Time

Platform

Smdiagnostics.dll

3.0.4506.8841

110,592

28-Mar-2020

13:37

x86

Smsvchost.exe

3.0.4506.8841

139,568

28-Mar-2020

13:37

x86

System.identitymodel.dll

3.0.4506.8841

446,464

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

System.servicemodel.washosting.dll

3.0.4506.8841

32,768

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

Big5.nlp

Not applicable

66,728

27-Oct-2017

23:27

Not applicable

Bopomofo.nlp

Not applicable

82,172

27-Oct-2017

23:27

Not applicable

Ksc.nlp

Not applicable

116,756

27-Oct-2017

23:27

Not applicable

Mscorlib.dll

2.0.50727.8813

4,558,848

28-Mar-2020

13:35

x86

Normidna.nlp

Not applicable

59,342

27-Oct-2017

23:27

Not applicable

Normnfc.nlp

Not applicable

45,794

27-Oct-2017

23:27

Not applicable

Normnfd.nlp

Not applicable

39,284

27-Oct-2017

23:27

Not applicable

Normnfkc.nlp

Not applicable

66,384

27-Oct-2017

23:27

Not applicable

Normnfkd.nlp

Not applicable

60,294

27-Oct-2017

23:27

Not applicable

Prc.nlp

Not applicable

83,748

27-Oct-2017

23:27

Not applicable

Prcp.nlp

Not applicable

83,748

27-Oct-2017

23:27

Not applicable

Sortkey.nlp

Not applicable

262,148

27-Oct-2017

23:27

Not applicable

Sorttbls.nlp

Not applicable

20,320

27-Oct-2017

23:27

Not applicable

Xjis.nlp

Not applicable

28,288

27-Oct-2017

23:27

Not applicable

Mscordacwks.dll

2.0.50727.8813

991,112

28-Mar-2020

13:35

x86

Mscorwks.dll

2.0.50727.8813

5,949,832

28-Mar-2020

13:35

x86

Sos.dll

2.0.50727.8813

390,536

28-Mar-2020

13:35

x86

Servicemonikersupport.dll

3.0.4506.8841

28,152

28-Mar-2020

13:37

x86

System.identitymodel.dll

3.0.4506.8841

446,464

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

For all supported x86-based versions

File name

File version

File size

Date

Time

Platform

Smdiagnostics.dll

3.0.4506.8841

110,592

28-Mar-2020

13:37

x86

Smsvchost.exe

3.0.4506.8841

139,568

28-Mar-2020

13:37

x86

System.identitymodel.dll

3.0.4506.8841

446,464

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

System.servicemodel.washosting.dll

3.0.4506.8841

32,768

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

Big5.nlp

Not applicable

66,728

27-Oct-2017

23:27

Not applicable

Bopomofo.nlp

Not applicable

82,172

27-Oct-2017

23:27

Not applicable

Ksc.nlp

Not applicable

116,756

27-Oct-2017

23:27

Not applicable

Mscorlib.dll

2.0.50727.8813

4,558,848

28-Mar-2020

13:35

x86

Normidna.nlp

Not applicable

59,342

27-Oct-2017

23:27

Not applicable

Normnfc.nlp

Not applicable

45,794

27-Oct-2017

23:27

Not applicable

Normnfd.nlp

Not applicable

39,284

27-Oct-2017

23:27

Not applicable

Normnfkc.nlp

Not applicable

66,384

27-Oct-2017

23:27

Not applicable

Normnfkd.nlp

Not applicable

60,294

27-Oct-2017

23:27

Not applicable

Prc.nlp

Not applicable

83,748

27-Oct-2017

23:27

Not applicable

Prcp.nlp

Not applicable

83,748

27-Oct-2017

23:27

Not applicable

Sortkey.nlp

Not applicable

262,148

27-Oct-2017

23:27

Not applicable

Sorttbls.nlp

Not applicable

20,320

27-Oct-2017

23:27

Not applicable

Xjis.nlp

Not applicable

28,288

27-Oct-2017

23:27

Not applicable

Mscordacwks.dll

2.0.50727.8813

991,112

28-Mar-2020

13:35

x86

Mscorwks.dll

2.0.50727.8813

5,949,832

28-Mar-2020

13:35

x86

Sos.dll

2.0.50727.8813

390,536

28-Mar-2020

13:35

x86

Servicemonikersupport.dll

3.0.4506.8841

28,152

28-Mar-2020

13:37

x86

System.identitymodel.dll

3.0.4506.8841

446,464

28-Mar-2020

13:37

x86

System.runtime.serialization.dll

3.0.4506.8841

970,752

28-Mar-2020

13:37

x86

System.servicemodel.dll

3.0.4506.8841

5,996,544

28-Mar-2020

13:37

x86

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