Microsoft Excel Security Feature Bypass Vulnerability

Summary

Microsoft Excel is affected by this vulnerability, which allows an attacker to bypass built-in security features. Successful exploitation could let malicious files avoid protections meant to warn users or block harmful content.

Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.

Timeline

1. Nov 10, 2021, 12:47 AM UTCCVE published
2. Nov 17, 2021Added to CISA KEV

   CISA has evidence of exploitation in the wild

3. Dec 1, 2021CISA remediation deadline

   Due date for US federal agencies to patch

4. Aug 19, 2026, 4:27 PM UTCRecord last updated
5. Oct 22, 2026EPSS reached 10%

   FIRST estimates at least a 10% chance of exploitation in the next 30 days

Affected versions

• Microsoft Microsoft 365 Apps for Enterprise

  From 16.0.1 · fixed in https://aka.ms/OfficeSecurityReleases

• Microsoft Microsoft Excel 2013 Service Pack 1

  From 15.0.0.0 · fixed in 15.0.5397.1001

• Microsoft Microsoft Excel 2016

  From 16.0.0.0 · fixed in 16.0.5239.1001

• Microsoft Microsoft Office 2013 Service Pack 1

  From 15.0.0 · fixed in 15.0.5397.1001

• Microsoft Microsoft Office 2016

  From 16.0.0 · fixed in 16.0.5239.1001

• Microsoft Microsoft Office 2019

  From 19.0.0 · fixed in https://aka.ms/OfficeSecurityReleases

• Microsoft Microsoft Office 2019 for Mac

  From 16.0.0 · fixed in 16.55.21111400

• Microsoft Microsoft Office LTSC 2021

  From 16.0.1 · fixed in https://aka.ms/OfficeSecurityReleases

• Microsoft Microsoft Office LTSC for Mac 2021

  From 16.0.1 · fixed in 16.55.21111400

References 1