Microsoft has confirmed that recent Windows updates include stricter identity checks that can break NTLM and Kerberos authentication on systems that share duplicate machine Security Identifiers (SIDs), causing repeated credential prompts, failed logins, inaccessible SMB shares and broken RDP...
Microsoft’s recent support bulletin and subsequent community reports have exposed a sharp operational edge of identity hardening: after installing October/September updates on Windows 11 (24H2 and 25H2) and Windows Server 2025, some environments experienced widespread Kerberos and NTLM...