KB5068865 Fixes Networking Parser Issue in Windows 11 23H2

Microsoft has pushed out the November 2025 Patch Tuesday update, KB5068865, for Windows 11 23H2. After installation, your system with 23H2 will move to Build 22621.6199.

While this release primarily focuses on security improvements, it also includes an important fix related to the Windows networking stack. The update resolves a problem with the HTTP.sys request parser, a core Windows component responsible for processing HTTP requests. Microsoft in the changelog notes:

This security update contains fixes and quality improvements from KB5068865 (released October 28, 2025). The following summary outlines key issues addressed by this update. Also, included are available new features. The bold text within the brackets indicates the item or area of the change.

• [Networking] Fixed: This update fixes an issue in the HTTP.sys request parser, a Windows component that reads and processes HTTP requests. The parser allowed a single line break within HTTP/1.1 chunk extensions, where the RFC 9112 standard requires a carriage return and line feed (CRLF) sequence to terminate each chunk. This can cause a parsing discrepancy when front end proxies are a part of the setup.
  
  To turn on strict parsing, use the following registry key:
  
• RegistryKey: [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Http\Parameters]
• Registry value: “HttpAllowLenientChunkExtParsing”=dword:00000000
• Data to be set: 0 

The update is available now through Windows Update and can also be downloaded manually from the Microsoft Update Catalog. Moreover, it’s worth noting that the November Patch Tuesday Update for Windows 11 version 24H2 and 25H2, under KB5068861, fixes the annoying Task Manager bug and a few other issues.