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Microsoft Security Response CenterCVE-2026-62799

Windows SMB Client Elevation of Privilege Vulnerability

HighVendor CVSS 7.8 / 10 1 CVE Published Aug 11, 2026 at 7:00 AM UTC

Summary

Heap-based buffer overflow in Windows SMB Client allows an authorized attacker to elevate privileges locally.

Products covered

  • Windows 11 version 26H1 for x64-based Systems

  • Windows 11 Version 26H1 for ARM64-based Systems

Remediation

Install KB5121000.

Vendor-listed fixes

  • 10.0.28000.2704

CVEs in this advisory 1

Update history

What changed in later vendor updates

SecurityAlert records field-level changes from the point we begin following a bulletin. Earlier vendor changes may not have a field-by-field record.

    • The vendor changed the advisory's last-updated date.
    • The vendor changed its remediation guidance.

Updates

  1. Published by Microsoft Security Response Center

    The publication date reported by the vendor.

  2. Added to SecurityAlert

    We collected the advisory from the official source.

  3. Updated by Microsoft Security Response Center

    The vendor changed the advisory after it was first published.

  4. Confirmed at the source

    Our collector saw this advisory during a later source check.