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Microsoft Security Response CenterCVE-2026-40360

Microsoft Excel Information Disclosure Vulnerability

Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.

Read the vendor bulletin Get alerts for Office Online Server
7.8CVSS out of 10High severity
Scope

What the vendor says is affected

  • Office Online Server
  • 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
  • Microsoft Office LTSC 2024 for 64-bit editions
  • Microsoft Office LTSC for Mac 2024
  • Microsoft Excel 2016 (32-bit edition)
  • Microsoft Excel 2016 (64-bit edition)

Versions the vendor lists as fixed

  • 16.0.10417.20128
  • https://aka.ms/OfficeSecurityReleases
  • 16.109.26051019
  • 16.0.5552.1000
Next step

What the vendor recommends

Click to Run Release Notes Install KB5002871. Install KB5002865.

Review the complete instructions on the vendor's site
Timeline

When this advisory changed

  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.

Vulnerabilities

CVEs named in this advisory

CVE-2026-40360View CVSS, KEV, EPSS, and threat context
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