Full Report
Microsoft has released Windows 10 KB5120249 cumulative update for versions 22H2 and 21H2 to fix security vulnerabilities and bugs. [...]
Analysis Summary
# Vulnerability: Windows 10 August 2026 Security Update (KB5120249)
## CVE Details
*Note: The provided text mentions the release of security updates but does not list individual CVE identifiers. Typically, Patch Tuesday updates address multiple vulnerabilities across the OS.*
- **CVE ID:** Multiple (Refer to Microsoft Security Update Guide for August 2026)
- **CVSS Score:** Varies (Typically ranging from Low to Critical)
- **CWE:** Varies (Commonly includes Memory Corruption, Elevation of Privilege, and Information Disclosure)
## Affected Systems
- **Products:** Microsoft Windows 10
- **Versions:**
- Windows 10 Version 22H2 (Build 19045.7663)
- Windows 10 Version 21H2 (Build 19044.7663)
- **Configurations:** All supported hardware configurations; specifically addresses systems using File History with SMB network shares and devices requiring Secure Boot certificate updates.
## Vulnerability Description
This cumulative update addresses multiple undisclosed security flaws as part of the "Patch Tuesday" cycle. Technically, it focuses on:
1. **File History Logic Error:** Fixes a bug where automatic backups to SMB network shares fail due to incorrect "invalid credentials" errors, preventing data redundancy.
2. **Secure Boot Management:** Deploys new Secure Boot certificates to a broader range of devices to ensure the integrity of the boot process and mitigate bootloader-level persistence by attackers.
## Exploitation
- **Status:** Information not provided in the source; typically, Patch Tuesday covers both "Not exploited" and "Exploited in the wild" flaws.
- **Complexity:** Varies
- **Attack Vector:** Varies (Network/Local)
## Impact
- **Confidentiality:** Varies (Potential for High impact in specific CVEs)
- **Integrity:** High (Addresses Secure Boot and system file integrity)
- **Availability:** High (Fixes a significant bug in File History backup services)
## Remediation
### Patches
- **Windows 10 22H2:** KB5120249 (Build 19045.7663)
- **Windows 10 21H2:** KB5120249 (Build 19044.7663)
### Workarounds
- No specific workarounds are provided; Microsoft recommends immediate installation of the mandatory cumulative update.
- For File History issues: Ensure network share permissions are verified until the patch is applied.
## Detection
- **Indicators of Compromise:** Failure of scheduled backups with "invalid credentials" despite correct settings; Secure Boot verification failures on outdated certificates.
- **Detection methods and tools:**
- Check OS Build version via `winver.exe`.
- Monitor Windows Update logs for successful installation of KB5120249.
- Review File History logs in Event Viewer.
## References
- **Vendor Advisories:** Microsoft Security Update Guide (August 2026)
- **Relevant links:**
- hxxps[://]www[.]catalog[.]update[.]microsoft[.]com/Search[.]aspx?q=windows%2010
- hxxps[://]www[.]bleepingcomputer[.]com/news/microsoft/windows-10-kb5120249-cumulative-update-released-with-fixes/