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CVE-2026-20858 Microsoft CVE debrief

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-01-13T18:16:14.647Z and has not been modified since then. The CVE-2026-20858 vulnerability is a use-after-free issue in Windows Management Services that could allow an authorized attacker to elevate privileges locally. The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. Affected products include various versions of Windows 10, Windows 11, and Windows Server. System administrators and security teams responsible for managing Windows-based systems, particularly those using Windows Management Services, should be aware of this vulnerability and take steps to mitigate it. This vulnerability allows an authorized attacker to elevate privileges locally, which could have significant impacts on system security. Affected systems should be prioritized for patching.

Vendor
Microsoft
Product
Windows 10 Version 1809
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-01-13
Original CVE updated
2026-07-30
Advisory published
2026-01-13
Advisory updated
2026-07-30

Who should care

System administrators and security teams responsible for managing Windows-based systems, particularly those using Windows Management Services, should be aware of this vulnerability and take steps to mitigate it.

Technical summary

The CVE-2026-20858 vulnerability is a use-after-free issue in Windows Management Services that could allow an authorized attacker to elevate privileges locally. The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. Affected products include various versions of Windows 10, Windows 11, and Windows Server.

Defensive priority

This vulnerability allows an authorized attacker to elevate privileges locally, which could have significant impacts on system security. Affected systems should be prioritized for patching.

Recommended defensive actions

  • Apply patches or updates provided by Microsoft to address the vulnerability in Windows Management Services.
  • Ensure that Windows Management Services are properly configured and secured.
  • Monitor system logs for potential exploitation attempts.
  • Implement additional security measures, such as access controls and intrusion detection systems.

Evidence notes

The CVE-2026-20858 record indicates a use-after-free vulnerability in Windows Management Services, which could allow an authorized attacker to elevate privileges locally. The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. Affected products include various versions of Windows 10, Windows 11, and Windows Server.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-20858 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-20858

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-20858 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-20858

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.