CVE-2026-50408: Microsoft Excel out-of-bounds read information disclosure

CVE-2026-50408 · Severity: medium · CVSS 5.5 · Published 2026-07-14

A security vulnerability has been identified in Microsoft Excel that could allow an unauthorized person to access sensitive information on a user's computer. To exploit this, an attacker would typically need to trick a user into opening a specially crafted Excel file. While this does not allow the attacker to take control of the system, it could lead to the exposure of private data stored in the computer's memory.

Technologies: Microsoft 365 Apps for Enterprise, Microsoft Excel 2016, Microsoft Office 2019, Microsoft Office 365 for Mac, Microsoft Office LTSC 2021, Microsoft Office LTSC 2024, Microsoft Office LTSC for Mac 2021, Microsoft Office LTSC for Mac 2024, Microsoft Office Online Server. Vendors: Microsoft.

Quick answers

Is CVE-2026-50408 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-50408 being exploited in the wild.
How severe is CVE-2026-50408?
Medium severity, with a CVSS score of 5.5, published 14 July 2026.
Which products and versions are affected?
Microsoft 365 Apps for Enterprise 16.0.1 to latest security release; Microsoft Excel 2016 16.0.0.0 to 16.0.5561.1001; Microsoft Office 2019 19.0.0 to latest security release; Microsoft Office 365 for Mac 1.0.0 to 16.111.26071215; and 5 more.
Is there a fix for CVE-2026-50408?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-50408 attacked?
It is attacked with local access, in a network appliance.
Am I affected by CVE-2026-50408?
Check whether you run Microsoft 365 Apps for Enterprise, Microsoft Excel 2016, Microsoft Office 2019 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An out-of-bounds read vulnerability (CWE-125) exists in Microsoft Excel across multiple versions, including Office 365, LTSC, and Office Online Server. The flaw is triggered when the application fails to properly validate input while reading from a memory buffer, potentially allowing an attacker to read data outside the intended memory space. Exploitation requires a local attack vector where a user is persuaded to open a malicious file (User Interaction required). Successful exploitation results in information disclosure, though it does not provide a direct path to remote code execution or data modification. Microsoft has released security updates to address this issue.

Affected products

  • Microsoft Microsoft 365 Apps for Enterprise 16.0.1 to latest security release
  • Microsoft Microsoft Excel 2016 16.0.0.0 to 16.0.5561.1001
  • Microsoft Microsoft Office 2019 19.0.0 to latest security release
  • Microsoft Microsoft Office 365 for Mac 1.0.0 to 16.111.26071215
  • Microsoft Microsoft Office LTSC 2021 16.0.1 to latest security release
  • Microsoft Microsoft Office LTSC 2024 16.0.0 to latest security release
  • Microsoft Microsoft Office LTSC for Mac 2021 16.0.1 to 16.111.26071215
  • Microsoft Microsoft Office LTSC for Mac 2024 16.0.0 to 16.111.26071215
  • Microsoft Office Online Server 16.0.0.0 to 16.0.10417.20175

Timeline

  • 2026-07-14: advisory: Initial publication by Microsoft and NVD

References

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