Microsoft has released a series of out-of-band Windows updates just six days after the September 2026 Patch Tuesday. The emergency updates address several bugs introduced by the September 8 security updates, including problems affecting Remote Desktop Services, Hyper-V Linux virtual machines, and USB Audio Class 1.0 devices.

The September 14 releases cover a wide range of Windows versions, including Windows 11, Windows 10, and several Windows Server editions.

For affected users and administrators, these updates are particularly important because some of the reported problems can prevent remote connections from working correctly or make servers and related Windows tools become unresponsive.

September Patch Tuesday Introduced Several Problems

Microsoft’s release notes confirm that the September 8, 2026 security updates introduced several known issues.

The most serious problems affect three main areas:

• Remote Desktop Services (RDS)
• Hyper-V folder sharing with Linux virtual machines
• Multichannel audio on certain USB Audio Class 1.0 devices

Microsoft has now released out-of-band updates to address the first two categories and part of the USB audio problem.

However, not every USB audio problem has been fixed yet.

Remote Desktop Connections Could Fail

One of the most important problems affects Remote Desktop Services.

After installing the September 2026 security updates, affected systems could experience RDS instability. Microsoft says this could cause:

• RDP connection failures
• Sign-in failures
• Servers becoming unresponsive while configuring Remote Desktop
• Microsoft Management Console (MMC) becoming unresponsive
• RDS Licensing Diagnoser problems
• File Explorer becoming unresponsive
• Windows Update pages failing to respond

This is particularly problematic for administrators managing Windows servers remotely.

Microsoft has addressed the RDS issue through the September 14 out-of-band updates. For example, KB5129195 fixes the problem on Windows 11 24H2 and 25H2, while KB5129194 addresses it on Windows 11 26H1.

Windows Server 2025 also receives a corresponding fix through KB5129235.

Hyper-V Linux VMs Could Lose Shared Folders

Another significant problem affects Hyper-V environments running Linux virtual machines.

The issue involves applications using HCS-managed virtual machines and the Plan 9 (9P) protocol to share folders between a Windows host and Linux guest.

After installing the September 8 updates, folders shared from the Windows host could:

• Completely disappear inside the Linux VM
• Become inaccessible
• Stop working as expected

This can affect workflows that rely on shared directories between Windows and Linux.

Microsoft has now included a fix for this issue in the affected Windows 11 out-of-band updates.

This is particularly relevant for developers and power users running Linux environments through virtualization.

USB Audio Problems Are Only Partially Fixed

The third major problem concerns certain USB Audio Class 1.0 devices.

The September 8 update could cause devices that worked correctly in normal stereo mode to fail when using multichannel audio configurations.

Microsoft specifically lists problems involving:

• 8-channel audio
• 3D audio modes
• Other multichannel configurations

The September 14 updates restore 8-channel and 3D audio functionality for affected devices. However, Microsoft explicitly warns that other USB audio problems remain unresolved.

Some affected devices can still experience:

• No audio output
• Volume controls stuck at zero
• Unresponsive sound settings
• Device Manager error Code 10
• The USB audio device failing to start

Microsoft says it is still working on a solution for these remaining problems.

So if your USB audio device is still broken after installing the new update, another Microsoft fix may be required.

11 Out-of-Band Updates Released

Microsoft released a surprisingly large number of emergency packages on September 14.

Here are the affected versions and corresponding KB numbers:

Microsoft’s documentation confirms that the updates address the RDS and audio problems across the affected Windows generations, while the Hyper-V/Plan 9 fix applies where supported.

Windows 11 Gets Additional Security Fixes

The emergency releases aren’t limited to bug fixes.

Some of the newer Windows 11 updates also include additional security protections.

Windows 11 26H1

KB5129194 includes protections for:

• CVE-2026-62721 — a Windows User-Mode Power Service elevation-of-privilege vulnerability
• CVE-2026-85921 — a Windows Secure Kernel Mode elevation-of-privilege vulnerability

Microsoft lists both vulnerabilities directly in the KB5129194 release notes.

Windows 11 24H2 and 25H2

KB5129195 includes protection for CVE-2026-62721, in addition to the non-security fixes for RDS, Hyper-V and USB audio.

This makes the emergency update more than simply a compatibility or bug-fix patch on these versions of Windows 11.

What About Windows 10?

Windows 10 users aren’t left out.

Microsoft has released several out-of-band packages covering supported Windows 10 editions, including:

• Windows 10 22H2
• Windows 10 Enterprise LTSC 2021
• Windows 10 Enterprise LTSC 2019
• Windows 10 Enterprise LTSB 2016

For example, KB5129236 addresses the RDS problem on Windows 10 22H2 and also fixes the 8-channel/3D USB audio issue. Microsoft continues to list the remaining USB Audio Class 1.0 problems as known issues.

Older Windows Server versions are also covered through their respective packages.

Windows Server 2012 and 2012 R2 Also Receive Emergency Updates

Microsoft has even released out-of-band updates for Windows Server 2012 and Windows Server 2012 R2 through the Extended Security Updates (ESU) program.

KB5129243 applies to Windows Server 2012 R2 ESU, while KB5129244 applies to Windows Server 2012 ESU.

Both updates address the RDS and USB audio problems.

However, administrators should remember that Windows Server 2012 and 2012 R2 reached the end of regular support in 2023. Their continued security updates depend on ESU eligibility.

Microsoft currently lists October 13, 2026 as the final date for these ESU programs.

How to Install the Emergency Windows Update

If you’re running Windows 11 26H1, 25H2, or 24H2, Microsoft distributes the applicable out-of-band update through Windows Update.

To check manually:

1. Open Settings.
2. Go to Windows Update.
3. Click Check for updates.
4. Install the available update.
5. Restart your PC if Windows requests it.

For example, Windows 11 24H2 and 25H2 users should look for KB5129195.

Windows 11 26H1 users should look for KB5129194.

You can confirm the installed update afterward by opening:

Settings → Windows Update → Update history

and searching for the corresponding KB number.

What If Windows Update Doesn’t Offer the Patch?

Some versions of Windows receive these packages differently depending on the edition and servicing channel.

Microsoft provides standalone packages through the Microsoft Update Catalog for supported systems and deployment scenarios.

For enterprise environments, administrators can also use the appropriate servicing tools and management channels.

The Windows Server 2012 and Server 2012 R2 updates, for example, are distributed through the Update Catalog rather than ordinary Windows Update for all scenarios.

Should You Install the Out-of-Band Update?

If your computer or server was affected by one of the bugs introduced by the September 8 Patch Tuesday update, the emergency release is specifically intended to address those problems.

The situation is particularly important for systems that depend on:

• Remote Desktop
• Windows Server administration
• Hyper-V Linux virtual machines
• Plan 9 folder sharing
• Multichannel USB audio

For Windows 11 26H1 and newer supported versions, the update also contains additional security protections.

That said, users with USB Audio Class 1.0 hardware should be aware that not every audio-related symptom has been resolved yet. Microsoft continues to investigate Code 10, missing audio output and unresponsive audio controls on affected devices.

How to Check Your Windows Version

If you’re unsure which update applies to your computer, press:

Windows + R

Then type:

winver

Press Enter.

Windows will display your installed version and OS build.

You can then match your Windows version with the appropriate KB package listed above.

Final Thoughts

Microsoft has moved unusually quickly to address several problems introduced by the September 8, 2026 Patch Tuesday.

The September 14 out-of-band updates tackle three major categories of problems: Remote Desktop failures, Hyper-V Linux folder-sharing issues, and multichannel USB audio problems.

The RDP issue is particularly significant for administrators because affected systems could reject remote connections or become unresponsive during Remote Desktop configuration. Microsoft has now addressed that problem across a broad range of Windows client and server versions.

The USB audio situation is slightly different. Microsoft has restored affected 8-channel and 3D audio functionality, but some devices can still experience Code 10, missing audio or broken volume controls. A further fix is still being developed.

If you installed the September 2026 Patch Tuesday update and have experienced RDP failures, missing Hyper-V shared folders, or USB audio problems, checking Windows Update for the September 14 out-of-band release is worthwhile.