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Microsoft Security Response CenterCVE-2026-78510

Microsoft Outlook and Word Remote Code Execution Vulnerability

CriticalVendor CVSS 8.4 / 10 1 CVE Published Sep 8, 2026 at 7:00 AM UTC

Summary

Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.

Products covered

  • Microsoft Office 2019 for 32-bit editions

  • Microsoft Office 2019 for 64-bit editions

  • Microsoft 365 Apps for Enterprise for 32-bit Systems

  • Microsoft 365 Apps for Enterprise for 64-bit Systems

  • Microsoft Office LTSC for Mac 2021

  • Microsoft Office LTSC 2021 for 64-bit editions

  • Microsoft Office LTSC 2021 for 32-bit editions

  • Microsoft Office LTSC 2024 for 32-bit editions

Show 5 more products
  • Microsoft Office LTSC 2024 for 64-bit editions

  • Microsoft Office LTSC for Mac 2024

  • Microsoft Office 2016 (32-bit edition)

  • Microsoft Office 2016 (64-bit edition)

  • Microsoft Office 365 for Mac

Remediation

Release Notes Install KB5002916.

Vendor-listed fixes

  • 16.0.10417.20207

  • 16.0.20326.20138

  • 16.113.26091433

  • 16.0.14334.20906

  • 16.0.17932.20976

  • 16.0.5569.1000

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 title.
    • The vendor changed the advisory summary.
    • CVSS changed from 9.8 to 8.4.
    • Added fixed versions: 16.113.26091433.

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.