Win Update KB5129195 Windows 11 Out-of-band Cumulative Update build 26100.9457 (24H2), 26200.9457 (25H2), and 26300.9457 (26H2) - Sept. 14



 Microsoft Support:

This out-of-band (OOB) update for Windows 11, version 25H2 and Windows 11, version 24H2 (KB5129195) is cumulative. It includes updates from previous releases, along with additional security and non-security improvements. Visit the Windows release health dashboard for the latest status on this release.

Improvements

This OOB update includes the following improvement:
  • [Security] This update includes protections documented in CVE-2026-62721, which refers to a Windows User-Mode Power Service (UMPS) Elevation of Privilege vulnerability.
  • [Remote Desktop Services (known issue)] Fixed: This update addresses an issue affecting Remote Desktop Services (RDS) after installing the September 2026 Windows security update (KB5122880). In affected environments, RDS might become unstable, causing RDP connection and sign-in failures or servers to become unresponsive during Remote Desktop configuration. Related tools, including Microsoft Management Console (MMC), RDS Licensing Diagnoser, File Explorer, and the Windows Update page, might also stop responding.
  • [Hyper-V (known issue)] Fixed: Some applications that use HCS-managed virtual machines experienced issues when sharing host folder with Linux VMs using Plan9. Folders shared from the Windows host using Plan9 did not appear or could not be accessed in the guest environment.
  • [8-channel or 3D audio modes] Fixed: Some USB Audio Class 1.0 devices functioning as expected in standard stereo configurations failed when using multichannel audio features, including 8-channel or 3D audio modes. (Note: There are other audio symptoms not resolved in this OOB update. See the “Known issues in this update” section for more information.)

Component updates

Windows 11 servicing stack update (KB5124007) - 22621.9441​

This update makes quality improvements to the servicing stack, which is the component that installs Windows updates. Servicing stack updates (SSU) ensure that you have a robust and reliable servicing stack so that your devices can receive and install Microsoft updates. To learn more about SSUs, see Simplifying on-premises deployment of servicing stack updates.

Known issues in this update

Symptoms

After installing the September 8, 2026, Windows security update, some USB Audio Class 1.0 devices might fail to start or produce audio. Affected devices might experience one or more of the following symptoms: The device displays an error in Device Manager: "This device cannot start (Code 10).” No audio output. Volume controls are unresponsive or remain at zero. Sound settings are unresponsive or unavailable. This issue is limited to USB Audio Class 1.0 devices.

Resolution
Microsoft is working on a resolution and will update this documentation when more information is available.

How to get this update

Before you install this update

Microsoft now combines the latest servicing stack update (SSU) for your operating system with the latest cumulative update (LCU). For general information about SSUs, see Servicing stack updates and Servicing Stack Updates (SSU): Frequently Asked Questions.

Install this update

To install this update, use one of the following Windows and Microsoft release channels.

Available
Next Step
Available
This update downloads and installs automatically from Windows Update and Microsoft Update.
Available
To install this update, download the standalone package(s) for this update from the Microsoft Update Catalog. This update contains MSU files that require installation in a specific order. Follow the Arm64 installation instructions or x64 installation instructions, as appropriate.

If you install additional Dynamic Update packages, use versions from the same release month as this update. If a Safe OS Dynamic Update or Setup Dynamic Update is not available for the same release month, use the most recently released version.

Note This latest cumulative update includes updates for AI components. AI components are applicable only to Copilot+ PCs and will not install on other Windows client PCs or Windows Server.

File Information

For a list of the files provided in this update, download the file information for cumulative update KB5129195.

For a list of the files provided in the servicing stack update, download the file information for SSU KB5124007 - versions 22621.9441.


 Source:



Check Windows Updates


ISO from Microsoft MCT:



UUP Dump:

64-bit ISO download:

ARM64 ISO download:

 
Last edited:
This problem with false Defender off notification showed up on another machine with public build after this update. So now I have 2 machines on public build with this problem. 😖🤬🤷‍♂️

Edition Windows 11 Pro
Version 25H2
Installed on ‎8/‎29/‎2025
OS build 26200.9457
Experience Windows Feature Experience Pack 1000.26100.360.0


View attachment 183002

View attachment 183003
View attachment 183004
My 2 Systems also have that Security off popup notification and KB5129195 did not fix the bug. same Windows build, different CPUs, both received the 2026 KEK keys, never had that Security off notification popup before. I submitted a feedback to MS.
1789642595304.webp
I also have a second bug on my System 1 only TPM 2.0 (a Secure-core feature for Acer AI PCs) that is enabled but Security Dashboard reports Disabled?
 
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My Computers My Computers

  • At a glance

    Windows 11 Home 25H2 build: 26200.9457Intel(R) Core(TM) Ultra 7 258V, 2200 Mhz, 8 C...32 GB LPDDR5X (soldered)Intel(R) Arc(TM) 140V GPU (16GB)
    OS
    Windows 11 Home 25H2 build: 26200.9457
    Computer type
    Laptop
    Manufacturer/Model
    Acer Swift Edge SFE14-51T
    CPU
    Intel(R) Core(TM) Ultra 7 258V, 2200 Mhz, 8 Cores
    Motherboard
    NB.JG411.004 mainboard, manufactured by Compal.
    Memory
    32 GB LPDDR5X (soldered)
    Graphics Card(s)
    Intel(R) Arc(TM) 140V GPU (16GB)
    Sound Card
    RealTek + Intel Smart Sound
    Monitor(s) Displays
    14" OLED matte Touch
    Screen Resolution
    2880 x1800 x120Hz
    Hard Drives
    KINGSTON OM8PGP41024Q-AA, NVMe Gen4, 1TB
    PSU
    65W USB-C charger
    Case
    Magnesium aluminum alloy body
    Cooling
    1 fan
    Keyboard
    US with Backlight
    Mouse
    Precision Trackpad
    Internet Speed
    25 Mb/s 5G
    Browser
    Edge
    Antivirus
    Windows Defender
    Other Info
    BIOS Version/Date: IInsyde Corp. V1.06, 3/16/2026, Windows Hello IR camera with Facial recognition. Secure Boot 2026 KEK key installed
  • At a glance

    Windows 11 Home 25H2 build: 26200.9457Intel 12th Gen. i7 12700H, 14 cores, 2.3 GHz ...8GB LPDDR4 on board + 8GB LPDDR4 3200 MHz in ...Intel Iris Xe supports up to 4096 x 2304 @ 120Hz
    Operating System
    Windows 11 Home 25H2 build: 26200.9457
    Computer type
    Laptop
    Manufacturer/Model
    Asus Vivobook K3502Z S15 15" OLED
    CPU
    Intel 12th Gen. i7 12700H, 14 cores, 2.3 GHz (24M Cache, up to 4.7 GHz, 6P+8E cores)
    Motherboard
    Alder Lake-H, 1700-4700 MHz clock rate
    Memory
    8GB LPDDR4 on board + 8GB LPDDR4 3200 MHz in Dual Channel.
    Graphics card(s)
    Intel Iris Xe supports up to 4096 x 2304 @ 120Hz
    Sound Card
    Harman Kardon - DTS
    Monitor(s) Displays
    OLED 15.6inch 2.8K (2880 x 1620)
    Screen Resolution
    16:9 aspect ratio 0.2ms response time 120Hz refresh rate, 550nits
    Hard Drives
    512GB M.2 NVMe Gen4 PCIe 4.0 SSD, Micron_2450_MTFDKBA512TFK
    PSU
    90-Watt USB charger (Thunderbolt4)
    Case
    Metal lid, plastic case
    Cooling
    1 fan
    Keyboard
    With adjustable backlight
    Mouse
    Precision Trackpad
    Internet Speed
    ISP provides 15 mb/s WIFI LTE (4G), laptop WIFI 6 adapter.
    Browser
    Edge
    Antivirus
    Windows Defender
    Other Info
    BIOS American Megatrends International, LLC. 10.1.2.312, 13/03/2024. Network adapter: Intel Wi-Fi 6E AX211 160 MHz, Secure Boot 2026 KEK key installed
Your SABRENT enclosure shows a drive as a Fixed Disk rather than a Removable Disk because of how the enclosure’s internal SATA/NVMe-to-USB bridge controller (such as ASMedia or Realtek chips) passes along hardware identifiers to your operating system. [1, 2]

What is the output of this PS command?
Code:
(Get-Volume -DriveLetter E  | Get-Partition | Get-Disk).IsReadOnly
 

My Computer My Computer

At a glance

Windows 7
OS
Windows 7
I use both!
Which is important, if you store your personal data on the same drive partition as Windows.

In that scenario, if you need to restore a drive image, you also need to restore the most current versions of your data...which may have changed since the image was made.
 

My Computer My Computer

At a glance

Windows 11 Pro 25H2
OS
Windows 11 Pro 25H2
Computer type
Laptop
Manufacturer/Model
Toshiba

My Computer My Computer

At a glance

Windows 11 Pro 25H2Intel I9-9900K64GBNVIDIA RTX 2060
OS
Windows 11 Pro 25H2
Computer type
PC/Desktop
Manufacturer/Model
Dell XPS 8930
CPU
Intel I9-9900K
Memory
64GB
Graphics Card(s)
NVIDIA RTX 2060
Sound Card
NVIDIA High Definition Audio
Monitor(s) Displays
4k Samsung
Screen Resolution
3840 x 2160
Hard Drives
512GB NVMe, ADATA SU 800, 2TB HDD
Thanks. I updated the script.
IsReadOnly will be $true or $false on normal drives, and CD/DVD's always report as $null. Therefore anything other than $false isn't a writable disk.
 

Attachments

My Computer My Computer

At a glance

Windows 7
OS
Windows 7
Today I got this update of Antimalware Client Version 4.18.26080.4 on my public Build 26200.9457 and that eliminated the problem with the false notification to turn defender on. I will need to verify on other machines, but it looks fine on this one now. 🤞

1789684807270.webp

1789684772492.webp
 

My Computer My Computer

At a glance

Windows 11 Pro 25H2Intel I9-9900K64GBNVIDIA RTX 2060
OS
Windows 11 Pro 25H2
Computer type
PC/Desktop
Manufacturer/Model
Dell XPS 8930
CPU
Intel I9-9900K
Memory
64GB
Graphics Card(s)
NVIDIA RTX 2060
Sound Card
NVIDIA High Definition Audio
Monitor(s) Displays
4k Samsung
Screen Resolution
3840 x 2160
Hard Drives
512GB NVMe, ADATA SU 800, 2TB HDD
Sadly, everyone from MS enjoys answering obscure enterprise questions, but no one responded to my AMA post (about Repair My PC). Well, they've been informed in public so they can't hide from it.

Next month if it's broken (26H2 GA) I will publish the repair script to GitHub.
 

My Computer My Computer

At a glance

Windows 7
OS
Windows 7
Thanks. I updated the script.
IsReadOnly will be $true or $false on normal drives, and CD/DVD's always report as $null. Therefore anything other than $false isn't a writable disk.
@garlin,
I got this with your latest script.
1789685581266.webp
 

My Computer My Computer

At a glance

Windows 11 Pro 25H2Intel I9-9900K64GBNVIDIA RTX 2060
OS
Windows 11 Pro 25H2
Computer type
PC/Desktop
Manufacturer/Model
Dell XPS 8930
CPU
Intel I9-9900K
Memory
64GB
Graphics Card(s)
NVIDIA RTX 2060
Sound Card
NVIDIA High Definition Audio
Monitor(s) Displays
4k Samsung
Screen Resolution
3840 x 2160
Hard Drives
512GB NVMe, ADATA SU 800, 2TB HDD
no one responded
I don't think Feedback Hub has either...

Why should they...you're fixing it for them ;-)

I'd ask you to publish it now...there are folks who currently need it.
 

My Computer My Computer

At a glance

Windows 11 Pro 25H2
OS
Windows 11 Pro 25H2
Computer type
Laptop
Manufacturer/Model
Toshiba
@garlin,
This looks better; I'll boot and verify if the "Repair my PC" works. Back in a minute. Thanks.

1789686440752.webp


Edit:
Repair my PC worked fine, thanks again. 👍
 
Last edited:

My Computer My Computer

At a glance

Windows 11 Pro 25H2Intel I9-9900K64GBNVIDIA RTX 2060
OS
Windows 11 Pro 25H2
Computer type
PC/Desktop
Manufacturer/Model
Dell XPS 8930
CPU
Intel I9-9900K
Memory
64GB
Graphics Card(s)
NVIDIA RTX 2060
Sound Card
NVIDIA High Definition Audio
Monitor(s) Displays
4k Samsung
Screen Resolution
3840 x 2160
Hard Drives
512GB NVMe, ADATA SU 800, 2TB HDD
I don't think Feedback Hub has either...

Why should they...you're fixing it for them ;-)

I'd ask you to publish it now...there are folks who currently need it.
I might need to tighten up the code. While it works, the trick is to make it user-proof (more error handling).
 

My Computer My Computer

At a glance

Windows 7
OS
Windows 7
I get that message on my Win 11 boxes AND my Win 10 box.
 

My Computers My Computers

  • At a glance

    Win 10 Pro / Win 11 Pro & Home, Linux MintAMD Ryzen 7 5700X / A10-7860K32GB / 16GBAMD RX 6650 XT / RX 580
    OS
    Win 10 Pro / Win 11 Pro & Home, Linux Mint
    Computer type
    PC/Desktop
    Manufacturer/Model
    Custom builds
    CPU
    AMD Ryzen 7 5700X / A10-7860K
    Motherboard
    MSI PRO B550-VC / ASRock A88M-G/3.1
    Memory
    32GB / 16GB
    Graphics Card(s)
    AMD RX 6650 XT / RX 580
    Monitor(s) Displays
    Samsung 27" / LG 24"
    Screen Resolution
    1920x1080
    Hard Drives
    Toshiba 2 TB
    Toshiba 1 TB
    Toshiba 1 TB
    WD Black SN770 1TB

    PNY 1 TB
    PNY 500 GB
    WD Black SN770 200 GB
    Inland 500 GB
    Inland 256 GB
    Case
    NZXT / Lian LI
    Keyboard
    ROCCAT PYRO / Logitech 148
    Mouse
    Logitech
    Browser
    Firefox, Opera, Waterfox, Tor
  • At a glance

    Windows 11 HomeIntel i516GB
    Operating System
    Windows 11 Home
    Computer type
    Laptop
    Manufacturer/Model
    HP 17
    CPU
    Intel i5
    Memory
    16GB
    Screen Resolution
    1920 x 1080
    Hard Drives
    512 GB
    Browser
    Firefox
I might need to tighten up the code. While it works, the trick is to make it user-proof (more error handling).
Isn't that a universal requirement for software? 🤣
 

My Computers My Computers

  • At a glance

    Win 11 Pro 25H2, Build 26200.9457Intel Core i5 14500, 14th Generation64GB DDR4GeForce RTX 4060
    OS
    Win 11 Pro 25H2, Build 26200.9457
    Computer type
    PC/Desktop
    Manufacturer/Model
    Home Brew
    CPU
    Intel Core i5 14500, 14th Generation
    Motherboard
    Gigabyte B760M G P WIFI
    Memory
    64GB DDR4
    Graphics Card(s)
    GeForce RTX 4060
    Sound Card
    Chipset Realtek
    Monitor(s) Displays
    LG 45" Ultragear & Acer 24" 1080p
    Screen Resolution
    5120x1440 & 1920x1080
    Hard Drives
    Crucial P310 2TB 2280 PCIe Gen4 3D NAND NVMe M.2 SSD (O/S)
    Silicon Power 2TB US75 NVMe PCIe Gen4 M.2 2280 SSD (backup)
    Crucial BX500 2TB 3D NAND (2nd backup)
    Seagate 4TB Ironwolf, rotating HDD secondary backup
    External off-line backup Drives: 2 NVMe 4TB drives in external enclosures
    PSU
    Thermaltake Toughpower GF3 750W
    Case
    LIAN LI LANCOOL 216 E-ATX PC Case
    Cooling
    Lots of fans!
    Keyboard
    Microsoft Comfort Curve 2000
    Mouse
    Logitech G305
    Internet Speed
    Verizon FiOS 1GB
    Browser
    Firefox
    Antivirus
    Malware Bytes & Windows Defender Security
  • At a glance

    Win 11 Pro 25H2, Build 26200.9168Intel Core i5 1440032GB DDR5Intel 700 Embedded GPU
    Operating System
    Win 11 Pro 25H2, Build 26200.9168
    Computer type
    PC/Desktop
    Manufacturer/Model
    Home Brew
    CPU
    Intel Core i5 14400
    Motherboard
    Gigabyte B760M DS3H AX
    Memory
    32GB DDR5
    Graphics card(s)
    Intel 700 Embedded GPU
    Sound Card
    Realtek Embedded
    Monitor(s) Displays
    27" HP 1080p
    Screen Resolution
    1920x1080
    Hard Drives
    Crucial P310 2TB NVMe Gen4 SSD
    Samsung EVO 990 2TB NVMe Gen4 SSD
    Samsung 2TB SATA SSD
    Seagate 4TB Ironwolf, rotating HDD secondary backup
    PSU
    Thermaltake Smart BM3 650W
    Case
    Okinos Micro ATX Case
    Cooling
    Fans
    Keyboard
    Microsoft Comfort Curve 2000
    Mouse
    Logitech G305
    Internet Speed
    Verizon FiOS 1GB
    Browser
    Firefox
    Antivirus
    Malware Bytes & Windows Defender Security
  • Nimo N171 17" Laptop, (Intel i3-1215U, 16GB RAM, 2TB NVMe, Win11 Pro)
    Acemagic Vista Mini PC V1 (Intel N150, 16GB RAM, 1TB NVMe, Win11 Pro)
    HP ENVY h8-1540t, (24GB RAM, 2TB SSD, 2TB HDD, Win11 Pro)

My Computers My Computers

  • At a glance

    Windows 11 Pro x64 25H2Ryzen 9 5900X64 GB G.Skill RipJaws V F4-3200C16D-64GVKASRock Steel Legend Arc B580 12 GB
    OS
    Windows 11 Pro x64 25H2
    Computer type
    PC/Desktop
    CPU
    Ryzen 9 5900X
    Motherboard
    ASRock B550 PG Velocita (UEFI-BIOS 3.90)
    Memory
    64 GB G.Skill RipJaws V F4-3200C16D-64GVK
    Graphics Card(s)
    ASRock Steel Legend Arc B580 12 GB
    Monitor(s) Displays
    Alienware AW3423DWF OLED ultrawide
    Hard Drives
    Samsung 990 Pro 1 TB NVMe SSD
    PSU
    eVGA Supernova 750 G3
    Case
    Corsair 275R
    Internet Speed
    VTel FTTH 1 Gb down and 1 Gb up
  • At a glance

    Windows 11 Home x64 25H2Ryzen 7 5800X3D32 GB (2x16 GB G.Skill TridentZ Neo)Sapphire Nitro+ Radeon RX 6750 XT
    Operating System
    Windows 11 Home x64 25H2
    Computer type
    PC/Desktop
    CPU
    Ryzen 7 5800X3D
    Motherboard
    Asus ROG Strix B550-F Gaming (UEFI-BIOS version 3644)
    Memory
    32 GB (2x16 GB G.Skill TridentZ Neo)
    Graphics card(s)
    Sapphire Nitro+ Radeon RX 6750 XT
    Hard Drives
    Samsung 970 Pro 512 GB NVMe SSD
    PSU
    Corsair RM850x
    Case
    Fractal Focus G
Isn't that a universal requirement for software? 🤣
Depends on your target audience. If I ask a technical user to run my PS script, they may already understand about changing their Execution Policy, or how to run a script with "-ExecutionPolicy Bypass", or you that have to sometimes include a "." in a leading filename for your script.

With a non-technical user, you can't take any details for granted and have to wrap everything up for them. Is the user's lack of expertise considered an "error" that needs to be covered? Your script gets to be 2-3X longer than where you started from.

If only a handful of people are going need the script once in a while, it's not worth my time. But if it's going to affect a lot more people, and can result in being truly helpful, then extra effort makes sense. The fact that MS has blissfully ignored this feature across all release channels tells me it's probably heading towards "OK let's do it."
 

My Computer My Computer

At a glance

Windows 7
OS
Windows 7
I started getting this notification after switching to 25H2 from 24H2 and after the OOB update was installed.
Got fixed on my Public Build 26200.9457 today, Sept 17, 2026. 🤞.

See Post #126 above.
 

My Computer My Computer

At a glance

Windows 11 Pro 25H2Intel I9-9900K64GBNVIDIA RTX 2060
OS
Windows 11 Pro 25H2
Computer type
PC/Desktop
Manufacturer/Model
Dell XPS 8930
CPU
Intel I9-9900K
Memory
64GB
Graphics Card(s)
NVIDIA RTX 2060
Sound Card
NVIDIA High Definition Audio
Monitor(s) Displays
4k Samsung
Screen Resolution
3840 x 2160
Hard Drives
512GB NVMe, ADATA SU 800, 2TB HDD
@Brink MS claims to have fixed the Defender notification problem with a new Defender update.

Windows 11, version 25H2 known issues and notifications
Incorrect notifications that "Microsoft Defender Antivirus is turned off"

Resolved: 2026-09-17, 18:22 PT
Opened: 2026-08-28, 15:34 PT

After installing the latest updates for Microsoft Defender Antivirus, notifications might appear stating that "Microsoft Defender Antivirus is turned off," even though the antivirus is functioning correctly and all settings show it as active. These notifications can appear when Windows starts and intermittently afterward. They persist even if notification settings are turned off.

This issue can be observed in any version of Windows or Windows Server with Microsoft Defender Antivirus running with the latest Defender updates.

Resolution: This issue was resolved in the Microsoft Defender Antivirus update (version 4.18.26080.4), released on September 17, 2026.

Affected platforms:
Client: Windows 11, version 26H1; Windows 11, version 25H2; Windows 11, version 24H2; Windows 11, version 23H2; Windows 10, version 22H2; Windows 10, version 21H2; Windows 10 Enterprise LTSC 2019; Windows 10 Enterprise LTSC 2016

Server: Windows Server 2025; Windows Server 2022; Windows Server 2019; Windows Server 2016; Windows Server 2012 R2; Windows Server 2012
 

My Computer My Computer

At a glance

Windows 7
OS
Windows 7

My Computer My Computer

At a glance

Windows 11 Pro 25H2Intel I9-9900K64GBNVIDIA RTX 2060
OS
Windows 11 Pro 25H2
Computer type
PC/Desktop
Manufacturer/Model
Dell XPS 8930
CPU
Intel I9-9900K
Memory
64GB
Graphics Card(s)
NVIDIA RTX 2060
Sound Card
NVIDIA High Definition Audio
Monitor(s) Displays
4k Samsung
Screen Resolution
3840 x 2160
Hard Drives
512GB NVMe, ADATA SU 800, 2TB HDD

My Computers My Computers

  • At a glance

    Windows 11 Pro x64 25H2Ryzen 9 5900X64 GB G.Skill RipJaws V F4-3200C16D-64GVKASRock Steel Legend Arc B580 12 GB
    OS
    Windows 11 Pro x64 25H2
    Computer type
    PC/Desktop
    CPU
    Ryzen 9 5900X
    Motherboard
    ASRock B550 PG Velocita (UEFI-BIOS 3.90)
    Memory
    64 GB G.Skill RipJaws V F4-3200C16D-64GVK
    Graphics Card(s)
    ASRock Steel Legend Arc B580 12 GB
    Monitor(s) Displays
    Alienware AW3423DWF OLED ultrawide
    Hard Drives
    Samsung 990 Pro 1 TB NVMe SSD
    PSU
    eVGA Supernova 750 G3
    Case
    Corsair 275R
    Internet Speed
    VTel FTTH 1 Gb down and 1 Gb up
  • At a glance

    Windows 11 Home x64 25H2Ryzen 7 5800X3D32 GB (2x16 GB G.Skill TridentZ Neo)Sapphire Nitro+ Radeon RX 6750 XT
    Operating System
    Windows 11 Home x64 25H2
    Computer type
    PC/Desktop
    CPU
    Ryzen 7 5800X3D
    Motherboard
    Asus ROG Strix B550-F Gaming (UEFI-BIOS version 3644)
    Memory
    32 GB (2x16 GB G.Skill TridentZ Neo)
    Graphics card(s)
    Sapphire Nitro+ Radeon RX 6750 XT
    Hard Drives
    Samsung 970 Pro 512 GB NVMe SSD
    PSU
    Corsair RM850x
    Case
    Fractal Focus G

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