Microsoft’s Sept. 14 emergency patch fixed two of the bugs it named in its own documentation and partly fixed a third — but two other widely reported Windows 11 problems, AMD graphics-driver crashes and File Explorer crashes, don’t appear in that documentation at all.
What happened, and what got fixed
On Sept. 8, Microsoft released KB5124008, its regular September “Patch Tuesday” update for Windows 11 versions 24H2 (build 26100.9445) and 25H2 (build 26200.9445). Microsoft’s own known-issues page for that update names three problems it caused: Remote Desktop Services became unstable, breaking RDP connections and sign-ins and leaving some servers unresponsive; a Hyper-V bug stopped Linux virtual machines using the Plan9 protocol from reaching shared folders on the host machine; and USB Audio Class 1.0 devices started failing to start, producing no sound, or showing a Device Manager error labeled Code 10.
Six days later, on Sept. 14, Microsoft shipped an out-of-band — meaning emergency, off-cycle — update, KB5129195, for the same two Windows versions, builds 26100.9457 and 26200.9457. Two sibling out-of-band updates went out the same day for other Windows 11 versions under different KB numbers: KB5129194 for 26H1 and KB5129242 for 23H2. KB5129195 itself does not apply to those two versions.
According to Microsoft’s own page, KB5129195 repairs the Remote Desktop Services instability and the Hyper-V/Plan9 folder-sharing bug in full. It fixes the USB audio problem only partly: it addresses, in Microsoft’s own wording, “the symptoms experienced on devices using 8-channel or 3D audio modes,” while the broader Code-10/no-audio failure remains open. On that point Microsoft’s page says: “Microsoft is working on a resolution and will update this documentation when more information is available.”
A month-old vulnerability, not a new one
KB5129195 also adds what Microsoft describes as additional protections for CVE-2026-62721, an elevation-of-privilege vulnerability in the Windows User-Mode Power Service rated 7.8 on the CVSS scale, which Microsoft classifies as “Important.” The Microsoft Security Response Center’s own records show the vulnerability was first published Aug. 11, 2026 — more than a month before this week’s patch. It is not a flaw discovered this week; the emergency update is closing a gap that had already been public and documented for over a month.
Two problems that don’t appear in Microsoft’s record at all
Several independent outlets — Windows Latest, Guru3D, TechSpot, PCWorld, fdaytalk.com and NotebookCheck among them — have reported two other kinds of failures appearing after the same September update, without Microsoft confirming a cause. One is graphics-driver trouble on AMD Radeon cards: timeouts, black screens and system freezes on models including the RX 6600, RX 7700 XT, RX 7800 XT, RX 7900 GRE, RX 7900 XTX and RX 9070 XT. The other is File Explorer crashing outright, a problem concentrated in enterprise and virtual-desktop environments running Citrix UPM, FSLogix, VMware Horizon or ProfileUnity ProfileDisks, in some cases leaving a PC on a black screen with no working desktop or taskbar.
Here the picture is more precise than a flat “unmentioned.” Microsoft’s KB5129195 page does name File Explorer once, but only as a related tool that “might also stop responding” during the now-fixed Remote Desktop Services instability — a different, already-resolved symptom, not the standalone Explorer.exe crashes enterprise users have reported. Neither KB5124008’s page nor KB5129195’s mentions AMD GPUs anywhere, in any context, and neither documents the separate, enterprise-concentrated Explorer.exe crash pattern as a known issue. That distinction matters: it is not a case of Microsoft acknowledging a bug and declining to fix it yet, the way the remaining USB-audio symptom is being handled — it is a case where problems multiple news outlets have documented independently simply do not appear, in that form, in Microsoft’s official account of either update. NotebookCheck, in an article published Sept. 15 and updated Sept. 16, put it this way: “Graphics driver crashes on select AMD hardware remain unaddressed. Sporadic explorer.exe crashes and File History backup failures from the September update will need a separate future fix.” A Windows Latest article dated Sept. 17 likewise described KB5129195 as an emergency fix “that still leaves AMD GPU errors unresolved,” in passing while covering an unrelated Windows 11 story — the closest thing to a same-day confirmation that both problems remain open.
What Microsoft has actually said
The one on-the-record Microsoft comment traced to these reports is a Reddit reply from Jason Parker, identified as a Microsoft employee, reported by Windows Latest on Sept. 12: “The September Windows updates were extensive and need more data to understand and root cause.” Windows Latest’s own account of the exchange says Parker “confirmed the company is looking into the reports and asked for memory dumps to investigate the root cause” — a characterization from Windows Latest’s reporting, not a quote from Parker himself.
That comment establishes awareness, not confirmation. It is not an official Microsoft blog post, not language on a support page, and not an apology. Separately, addressing one specific rollback report, Microsoft told Windows Latest that it “has not confirmed that either update causes the problem.” Those are two different statements carrying two different weights: one Microsoft employee acknowledging that reports exist and asking for diagnostic data is not the same thing as Microsoft accepting responsibility for the AMD GPU bug.
What still isn’t known
No source — not Microsoft, not any of the independent outlets that covered the story — has published a percentage, a raw count, or any telemetry figure for how many systems are hitting the AMD GPU or File Explorer problems. Every account so far is qualitative: “some PCs,” “reports.” QuestReviewCenter put that limitation directly, describing the issue as “documented as anecdotal, sourced from user reports on Reddit … rather than official telemetry data.” No timeline for a fix exists either; fdaytalk.com reported plainly that “Microsoft has not committed to a timeline.” And no statement from AMD, about its own drivers or about the Windows update generally, turned up anywhere.
A pattern, not an isolated incident
Counting this one, Microsoft has shipped five out-of-band Windows 11 updates in 2026, per Microsoft’s own release-health records. Jan. 17 brought KB5077744, fixing Remote Desktop sign-in failures introduced by the Jan. 13 monthly security update, KB5074109 — itself a regular release, not an out-of-band one, though Windows Latest separately reported it had also caused boot failures, an “UNMOUNTABLE_BOOT_VOLUME” error, on some commercial PCs, which Microsoft described at the time as “currently limited to commercial PCs.” A second January out-of-band update, KB5078127, followed on Jan. 24, fixing a bug that made some apps unresponsive or produced errors saving files to cloud storage such as OneDrive or Dropbox. In March, two more followed: KB5085516 on March 21 repaired a Microsoft-account sign-in failure, and KB5086672 on March 31 fixed an installation error tied to a non-security preview update released five days earlier. The Register argued in a Feb. 2 opinion piece that Microsoft’s own “out-of-band” label has become misleading, since such follow-up patches now arrive “every Patch Tuesday update” — an assessment from The Register, not a description Microsoft itself has used.
KB5129195 installs automatically through Windows Update, through Windows Update for Business, by manual download from the Microsoft Update Catalog, or through WSUS for managed enterprise deployments.
Sources and further reading
- CVE-2026-62721 Security Update Guide
- September 14, 2026—KB5129195 (OS Builds 26200.9457 and 26100.9457) Out-of-band
- September 8, 2026—KB5124008 (OS Builds 26200.9445 and 26100.9445)
- Windows 11 – release information
- January 17, 2026—KB5077744 Out-of-band
- January 24, 2026—KB5078127 Out-of-band
- March 21, 2026—KB5085516 Out-of-band