Blog Post

Ask the Directory Services Team
5 MIN READ

What is going on with RC4 in Kerberos?

WillAftring's avatar
WillAftring
Icon for Microsoft rankMicrosoft
Jan 26, 2026
  Howdy everyone! The cat is out of the bag when it comes to Microsoft’s forward outlook on RC4 usage in Kerberos. In the past few months, we have published the following.  Beyond RC4 for Windo...
Updated Jan 26, 2026
Version 1.0
aes
Kerberos
RC4
WillAftring
rk2014's avatar
rk2014
Copper Contributor
Feb 08, 2026

WillAftring​ I hope you are doing well!

I am writing to seek clarification regarding the behavior of the Windows Cumulative Updates scheduled for release in July 2026.

The current documentation states that while the behavior will be identical to the April 2026 updates, users will no longer have the option to roll back to audit mode. Could you please clarify if this means the "DefaultDomainSupportedEncTypes" exception will also cease to function after the July patch is applied?

 

If that is the case, I am concerned about the potential impact on customers still running business-critical applications on Windows Server 2003 that rely on domain-based authentication.

I look forward to your guidance on how this update might affect these legacy environments.

Thanks,

Raj