Microsoft’s January 2026 security update has disrupted enterprise Remote Desktop infrastructure, triggering widespread credential prompt failures that prevent users from accessing Azure Virtual Desktop and Windows 365 environments.
The problematic patch KB5074109, released January 13, 2026, introduced an authentication regression affecting Windows 11 versions 24H2 and 25H2 running builds 26100.7623 and 26200.7623.
The issue manifests as immediate sign-in failures when employees attempt to connect via Remote Desktop through the Windows App.
Users encounter “Unable to Authenticate” errors and error code 0x80080005 before sessions can establish, despite entering valid credentials.
The authentication interface fails to process login information correctly, preventing the connection handshake between client devices and remote environments from completing.
Enterprise IT departments faced immediate operational disruption as the Windows App serves as the primary gateway for cloud-hosted workstations.
The regression impacts organizations relying on virtualized desktop infrastructure for hybrid work, with help desks reporting surges in failed connection attempts following the update deployment.
The technical root cause lies in changes to how the Windows App handles credential prompts on specific builds.
Microsoft’s investigation confirmed that the January security update introduced a client-side regression affecting authentication validation traffic, straining the Azure Virtual Desktop connection-handling layers.
The credential prompt failure affects a broad range of Windows versions beyond the initially reported builds.
| Operating System | Version | Remediation KB | Status |
|---|---|---|---|
| Windows 11 | 25H2 | KB5077744 | Resolved |
| Windows 11 | 24H2 | KB5077744 | Resolved |
| Windows 11 | 23H2 | KB5077797 | Resolved |
| Windows Server | 2025 | KB5077793 | Resolved |
| Windows Server | 2022 | KB5077800 | Resolved |
| Windows Server | 2019 | KB5077800 | Resolved |
| Windows 10 | 22H2 | Pending | Under Investigation |
| Windows 10 | 21H2 | Pending | Mitigated |
| Windows 10 Enterprise LTSC | 2019 | Pending | Under Investigation |
Windows 11 23H2 systems running KB5073455 experienced similar authentication failures. At the same time, Windows Server editions 2019 through 2025 and Windows 10 Enterprise LTSC releases also exhibited Remote Desktop login issues.
Microsoft Deploys Emergency Out-of-Band Fix
Microsoft acknowledged the issue through automated service monitoring after detecting an increase in failed connection attempts and expedited an out-of-band remediation patch.
On January 17, 2026, the company released an emergency update KB5077744 for Windows 11 25H2 and 24H2 systems, incrementing affected builds to 26200.7627 and 26100.7627.
The out-of-band update specifically targets the authentication regression without requiring removal of the original security update, ensuring systems retain protections against January vulnerabilities while restoring Remote Desktop functionality.
Until deploying the remediation patch, administrators implemented several workarounds. Organizations switched users to the legacy Remote Desktop Client for Windows or directed access through the Windows App web client.
Microsoft, though, does not represent optimal long-term solutions. Microsoft made a Known Issue Rollback available, though limited visibility delayed initial awareness.windowsforum+3
System administrators should immediately deploy KB5077744 across enterprise endpoints to restore service availability.
The January 2026 security update addressed 114 vulnerabilities, including the actively exploited zero-day CVE-2026-20805, making its deployment critical despite the authentication regression.
Organizations affected by credential failures should verify the status of remediation patch installations and prioritize deployment to prevent continued productivity losses.
Follow us on Google News, LinkedIn, and X to Get Instant Updates ancd Set GBH as a Preferred Source in Google.