![\"Windows](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/11\/1762174328_70_960x0.jpg\")
<\/p>\n<\/p>\n
Microsoft confirms Windows update NTLM and Kerberos authentication issues.<\/p>\n
SOPA Images\/LightRocket via Getty Images<\/p>\n
Hot on the heels of the NSA publishing a \u201chigh-risk of compromise<\/a>\u201d alert for Microsoft Exchange server users, and the CVE-2025-9491 Windows vulnerability being exploited by attackers with no patch available<\/a>, comes more bad news. Microsoft has confirmed another Windows update issue, this time impacting Windows 11 and Windows Server users, that leads to the repeated prompting for authentication credentials, the failure of valid credentials, and remote desktop connections. Here\u2019s what you need to know and do.<\/p>\n ForbesMicrosoft Confirms Free Windows 10 Security Updates \u2014 How To Get ThemBy Davey Winder<\/a>Microsoft Confirms Some Users Might Experience Authentication Failures After Windows 11 And Server Updates<\/p>\n Microsoft is continually evolving the security protections available to users of the Windows operating systems, as evidenced in the recent announcement of new functionality to help keep admin users safe<\/a> from malicious applications and actors threatening accounts. Sometimes, these updates can cause issues, even through they are ultimately there to enhance security rather than make your life miserable for no reason. Such would appear to be the case with the latest confirmation from Microsoft that \u201cadded security protections that enforce checks on Security IDs\u201d put into place with Windows 11 and Server updates<\/a> \u201creleased on and after August 29,\u201d could be causing authentication failures for some users.<\/p>\n Microsoft Support posting KB5070568<\/a> explained that users \u201cmight experience Kerberos and New Technology LAN Manager authentication failures across devices that have duplicate Security IDs.\u201dThese NTLM and SID issues are impacting users of Windows 11, version 24H2, Windows 11, version 25H2, and Windows Server 2025 following the August 29 update. <\/p>\n ForbesNew Proton Research Exposes 300 Million Stolen CredentialsBy Davey Winder<\/a><\/p>\n This is caused by those aforementioned security protections, which, Microsoft confirmed, \u201cenforce checks on SIDs, causing authentication to fail when devices have duplicate SIDs.\u201d This is a good thing. Such duplicate SIDs are often created when performing \u201cunsupported cloning or duplication of a Windows installation without running Sysprep.\u201d SID uniqueness, enabled by Sysprep, is now a mandatory requirement for those Windows versions post-update. Without the new enforcements, it was possible for an unauthorized user to potentially get access to restricted files that were accessible on the duplicated SID system.<\/p>\n \u201cThis design change blocks authentication handshakes between such devices,\u201d Microsoft said, adding that \u201cdevices containing duplicate SIDs will need to be rebuilt using supported methods<\/a> for cloning or duplicating a Windows installation so that they have unique SIDs.\u201d<\/p>\n