Full Report
Microsoft released an emergency update to fix the March 2026 KB5079391 non-security preview update, which was pulled over the weekend due to installation issues. [...]
Analysis Summary
# Vulnerability: Windows 11 Update Installation Failure (Error 0x80073712)
## CVE Details
*Note: This specific issue is a functional regression/installation failure rather than a security vulnerability with a CVE assignment. However, it affects the delivery of security patches.*
- **CVE ID:** N/A (Functional Bug)
- **CVSS Score:** N/A
- **CWE:** CWE-404 (Improper Resource Shutdown or Release - related to update file corruption/missing files)
## Affected Systems
- **Products:** Windows 11
- **Versions:**
- Windows 11, version 24H2
- Windows 11, version 25H2
- **Configurations:** Systems attempting to install the March 2026 non-security preview update (KB5079391).
## Vulnerability Description
The issue involves a failure in the Windows Update servicing mechanism during the installation of cumulative update KB5079391. Users encountered error code **0x80073712**, which indicates that "Some update files are missing or have problems." This prevented the successful deployment of 29 planned changes, including improvements to Smart App Control and Display settings. While the KB5079391 update itself is a "non-security preview," its failure can disrupt the servicing stack's ability to apply subsequent updates.
## Exploitation
- **Status:** Not exploited (This is a reliability issue, not a security flaw).
- **Complexity:** N/A
- **Attack Vector:** Local (Triggered via Windows Update process).
## Impact
- **Confidentiality:** None
- **Integrity:** Medium (Update process failure leads to inconsistent system states).
- **Availability:** Low (Prevents deployment of new features and potential stability improvements).
## Remediation
### Patches
Microsoft has released an out-of-band (OOB) emergency update to resolve the installation loop and supersede the broken preview update:
- **KB5086672:** For Windows 11 versions 24H2 and 25H2. This update includes all protections from the March 2026 security updates plus the installation fix.
### Workarounds
- Users can manually check for the new update via **Settings > Windows Update** and select **Download & install**.
- If the system is stuck in an error loop, clearing the Windows Update cache (`C:\Windows\SoftwareDistribution`) may be required before applying the OOB fix.
## Detection
- **Indicators of Compromise:** N/A
- **Detection Methods:**
- Monitor Windows Update logs for **Error Code 0x80073712**.
- Verify if **KB5079391** is flagging "missing files" in the Update history.
- Check for the existence of **KB5086672** to confirm the fix has been applied.
## References
- Microsoft Message Center: [https://learn.microsoft.com/en-us/windows/release-health/windows-message-center#3809]
- Microsoft Support Advisory: [https://support.microsoft.com/help/5086672]
- Original Issue Report: [https://www.bleepingcomputer.com/news/microsoft/microsoft-pulls-windows-kb5079391-update-over-0x80073712-install-errors/]