Seven weeks after the September 8 Windows security update broke audio on some USB devices, Microsoft's status for the bug is still Mitigated rather than Resolved. On the Windows 11 version 25H2 release health page, every other listed known issue now reads Resolved.
The entry is logged against OS Build 26200.9445, delivered by KB5124008 on September 8, 2026. Microsoft opened it on September 25 and last touched it on September 29, a month ago.
What Mitigated means on Microsoft's own scale
These are defined terms, not loose labels. Microsoft publishes a status definitions table for its release health pages.
Mitigated means "a workaround is available and communicated to Windows customers". An issue stays there "until a KB article is released by Microsoft to resolve the known issue".
Resolved is the higher bar, and means a documented solution has shipped. Investigating sits below both, covering issues where scope and root cause are still being gathered.
So Mitigated is not a fix, and Microsoft is not claiming one here.
Why USB Audio Class 1.0 devices are the ones failing
Microsoft is specific about scope. The documentation says the issue "is limited to USB Audio Class 1.0 devices".
Windows serves the two USB audio class specifications with two separate built-in drivers. The older one, usbaudio.sys, implements release 1.0 of the class definition and has been in Windows since Windows 98.
The Class 2.0 driver is a different file, usbaudio2.sys. According to Microsoft's driver notes, it only started shipping with Windows 10 release 1703.
That date explains the pattern. Hardware built to work on Windows without a vendor driver before 2017 generally had to present itself as Class 1.0.
Cheaper headsets, long-serving audio interfaces and plain USB DACs are the likeliest to sit on that older path. Devices that enumerate as Class 2.0 load the newer driver and fall outside the scope Microsoft has described.
There is one documented wrinkle. Microsoft notes that a Class 2.0 device with MIDI still enumerates its MIDI function separately, with the 1.0 driver loaded.
The out-of-band update addressed one symptom out of five
Microsoft lists five symptoms. Device Manager reports "This device cannot start (Code 10)", there is no audio output, and volume controls are unresponsive or stuck at zero.
Sound settings can be unresponsive or unavailable. Some devices work in plain stereo but fail in 8-channel or 3D audio modes.
An out-of-band update released on September 14, KB5129195, arrived six days after the original update. It addressed the last of those symptoms only.
Microsoft's own wording on the remainder is plain. "We are working to address the other symptoms and will update this documentation when more information is available."
Switching to 2-channel mode had been a customer-reported way to restore sound in the multichannel case. Microsoft records that behaviour as resolved by the September update, so it is no longer the answer for anyone already patched.
When this site covered the September update's unfixed audio bugs, a full fix was expected at the October 13 Patch Tuesday. That date has passed without one.
Windows 11 26H2 carries its own entry with no partial fix
The 26H2 release health page logs a separate record for the same fault. It was opened on September 11, two weeks before the 25H2 entry, and is attributed to installing 26H2 rather than to KB5124008.
That version lists four symptoms, dropping the multichannel bullet, and carries no Resolution section at all. In its place Microsoft writes that it is "working to address this issue in a future Windows update".
The affected platform list is unusually long either way. It runs from Windows 11 26H2 back to Windows 10 Enterprise LTSC 2016, and on the server side from Windows Server 2025 back to Windows Server 2012.
What an affected reader can actually do today
Microsoft publishes no consumer workaround for this issue. The only route it names is for organisations, directing IT administrators who need an immediate workaround to contact Microsoft Support for Business.
That is a gap worth naming, given that the Mitigated label rests on a workaround having been communicated to customers. Standard audio troubleshooting such as checking USB selective suspend is unrelated to this fault and will not clear a Code 10 caused by it.
The contrast on the same page is sharp. A second bug from that same KB5124008, affecting domain-joined devices, was opened on September 16 and resolved six days later.
Three more issues closed this month. Remote Desktop error 0xC000000D was resolved on October 28 by KB5127936, while a black-screen problem and the Dolby Digital AC-3 decoding crash were both closed on October 13 by KB5127648.
Microsoft has not published a root cause, a target update or any estimate of how many devices are affected. No list of affected models exists either, so the practical test remains whether a device identifies as Class 1.0 in Device Manager.
The status can change at any time, and the release health entry is the only place Microsoft commits to recording it.
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