Full Report
Microsoft confirmed over the weekend that some games and applications using AC-3 (Dolby Digital) audio decoding will crash after installing the September 2026 KB5124010 Windows 11 preview update. [...]
Analysis Summary
# Vulnerability: AC-3 Audio Decoding Crash in Windows 11 KB5124010
## CVE Details
* **CVE ID:** N/A (Functional Regression / Stability Issue)
* **CVSS Score:** N/A
* **CWE:** N/A
*Note: This is currently classified as a functional bug/known issue resulting from a Windows update rather than a documented security vulnerability (CVE).*
## Affected Systems
* **Products:** Microsoft Windows 11
* **Versions:** Windows 11, version 24H2
* **Configurations:** Systems with the **September 2026 KB5124010** preview update installed. The issue specifically affects devices where the "Get the latest updates as soon as they're available" option is enabled, causing the optional update to install automatically.
## Vulnerability Description
A regression in the Windows built-in audio decoding component causes applications and games relying on **AC-3 (Dolby Digital)** decoding to malfunction. The flaw triggers when an application attempts to utilize the legacy Windows audio decoding stack. Impacted applications may fail to launch, close without warning, or crash specifically when audio playback (such as music or in-game sound) is initiated. Modern applications that bundle their own proprietary codecs are generally unaffected.
## Exploitation
* **Status:** Not exploited (Stability issue)
* **Complexity:** N/A
* **Attack Vector:** N/A
## Impact
* **Confidentiality:** None
* **Integrity:** None
* **Availability:** **High** (Causes application crashes, prevents software from launching, and disrupts core functionality of media/gaming software).
## Remediation
### Patches
* **Status:** Pending. Microsoft is currently working on a resolution.
* **Current Version:** Affected users are currently on KB5124010.
### Workarounds
* **Uninstall Update:** Users experiencing crashes can uninstall the optional KB5124010 update via *Settings > Windows Update > Update history > Uninstall updates*.
* **Disable Automatic Previews:** Disable the toggle for "Get the latest updates as soon as they're available" to prevent the automatic installation of optional preview builds in the future.
* **Use Alternative Decoders:** If available, configure the affected application to use a third-party or integrated audio engine rather than the Windows system default.
## Detection
* **Indicators of Compromise:** N/A (Non-security event).
* **Detection Methods:**
* Monitor Event Viewer for application crashes (Event ID 1000) associated with audio components after the installation of KB5124010.
* Verify the presence of KB5124010 in the installed updates list.
## References
* **Vendor Advisory:** Microsoft Windows Release Health Dashboard [hXXps://learn[.]microsoft[.]com/en-us/windows/release-health/status-windows-11-26h2#applications-which-require-ac-3-audio-decoding-might-close-unexpectedly]
* **News Coverage:** BleepingComputer Article [hXXps://www[.]bleepingcomputer[.]com/news/microsoft/microsoft-windows-kb5124010-update-crashes-some-games-and-apps/]