Windows bugs and fixes October 22 2026: status

What broke in the latest Windows updates?

BleepingComputer says KB5124010 caused AC-3 games and Windows 11 apps to crash. According to BleepingComputer, the failures followed the optional September 2026 preview update and affected software using Windows' built-in AC-3 (Dolby Digital) audio decoding on Windows 11 24H2 and later.

BleepingComputer records several symptoms on an affected computer: an application can fail to launch, close without warning, or work until music playback calls the decoder. BleepingComputer adds that many modern apps include their own audio decoding components and were not affected by the Windows decoder problem after the preview update.

KB5124010 required a click on “Download and install,” according to BleepingComputer, unless “Get the latest updates as soon as they're available” was enabled and allowed automatic installation. That distinction helps identify exposure. I would check update history before treating every game or application crash as the same Windows 11 bug.

The network problem has a different cause and symptom set. According to Neowin, KB5127648 and KB5126646 changed authentication enforcement and can disrupt Wi-Fi, Ethernet, and VPN connections that depend on MS-CHAPv2-based authentication. I would keep those failures separate from the AC-3 crashes because their fixes and workarounds are different.

Which Windows fixes have shipped?

PCWorld says KB5127648 fixes the Windows 11 black screen after sign-in. According to PCWorld, Explorer.exe could fail to start or repeatedly crash in multi-user environments such as Azure Virtual Desktop and FSLogix, preventing the desktop from loading.

PCWorld identifies Windows 11 24H2, 25H2, and 26H2 as eligible for KB5127648, which is available now and includes the Windows Explorer known-issue fix for affected computers. The report says the problem first appeared after the August Windows update. My earlier Windows status report provides continuity for readers tracking the same servicing cycle.

According to BleepingComputer, KB5127648 also addresses the AC-3 decoding crashes introduced by KB5124010, and Microsoft advised affected Windows 11 24H2 and later users to install the latest security update. That makes KB5127648 the relevant Windows update fix for both documented symptoms, although neither report says every black screen or application crash shares these causes.

I would match the symptom before applying the conclusion. A black screen after sign-in in a multi-user environment points toward the Explorer fix. A game or app that fails around AC-3 playback points toward the decoder fix.

Which Windows known issues remain unfixed?

Neowin says no permanent fix has shipped for the network-authentication break. According to Neowin, Windows 11 24H2, 25H2, and 26H2 and Windows Server 2025 are affected when Windows switches to Enforcement mode by default while Credential Guard is disabled.

Neowin says administrators who cannot migrate affected systems immediately can temporarily set BlockNtlmv1SSO to 0 under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0, restoring Audit mode while Microsoft works on a permanent solution. The report warns that a restart may be required. The cost is reduced enforcement and an administrative registry change that must later be reviewed.

According to BleepingComputer, some devices running Windows 11 version 24H2 and later cannot enable Smart App Control after KB5127648 because its Windows Security option becomes grayed out. BleepingComputer says Microsoft has not released a fix, but enterprise administrators can use a registry modification or install and enable the provided Group Policies before restarting affected devices.

The Smart App Control workaround costs administrative time and a policy change. It does not turn the workaround into a shipped repair. I would record which workaround was applied so it can be removed or reassessed when Microsoft publishes a permanent fix.

What can a Windows user do today?

Install KB5127648 when the symptom matches a documented repair, and use the temporary workaround only for the unresolved issue. BleepingComputer reports that Microsoft recommends installing KB5127648 on affected systems running Windows 11 24H2 and later.

First, open update history and check for KB5124010 or KB5127648. If AC-3 games or applications started crashing after KB5124010, install the current security update. If a multi-user computer shows a black screen after sign-in because Explorer.exe fails, install KB5127648 and restart.

If Smart App Control is grayed out, do not invent a registry value. Ask the administrator responsible for the computer to use Microsoft's documented registry or Group Policy workaround. BleepingComputer says no fix is available yet; enterprise administrators can modify the registry or install the provided Group Policies, and the Group Policy route requires enabling both settings and restarting affected devices.

If Wi-Fi, Ethernet, or VPN authentication broke after the current update, ask an administrator to confirm whether the connection uses MS-CHAPv2-based authentication. Neowin's temporary route is BlockNtlmv1SSO set to 0, which restores Audit mode and may require a restart while Microsoft prepares a permanent solution.

I would not uninstall a security update solely because another computer has a similar symptom. Match the installed KB, Windows version, environment, and failure first. Microsoft’s public issue records and the cited reports already provide concrete actions for the documented cases.