RC4 in Active Directory: The silent risk that’s harder to find than you think

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RC4 is a legacy encryption algorithm that Kerberos has relied on for decades to secure authentication traffic in Active Directory (AD) environments. That’s about to change—whether your environment is ready or not.  As part of the security hardening tied to CVE-2026-20833, Microsoft is phasing out RC4 encryption in Kerberos authentication. The April 2026 Windows update marks the first phase where Kerberos Key […]