CVE-2026-26166

Local privilege escalation via Windows Shell double free

Published Apr 14, 2026 · Updated Apr 14, 2026

Double free in Windows Shell in supported Microsoft Windows 11 and Windows Server releases allows local users to elevate privileges. Microsoft identifies a double-free memory-management error in Windows Shell but has not disclosed the affected function, object lifecycle, or trigger input. A low-privileged local user must satisfy a high-complexity condition; successful exploitation gains elevated Windows privileges without user interaction.

CVSS severity7.0
High
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Double free in Windows Shell in supported Microsoft Windows 11 and Windows Server releases allows local users to elevate privileges. Microsoft identifies a double-free memory-management error in Windows Shell but has not disclosed the affected function, object lifecycle, or trigger input. A low-privileged local user must satisfy a high-complexity condition; successful exploitation gains elevated Windows privileges without user interaction.

The record

CVE
CVE-2026-26166
Published
Apr 14, 2026
Updated
Apr 14, 2026
Vendor
Microsoft
Product
Windows Server 2025 (Server Core installation)
Classifications
CWE-415, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.0.26100.0 <10.0.26100.32690

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.32690
Microsoft · Windows 11, version 25H2version=10.0.26200.0 <10.0.26200.8246
Microsoft · Windows 11, version 24H2version=10.0.26100.0 <10.0.26100.32690
Microsoft · Windows Server 2022, 23H2 Edition (Server Core installation)version=10.0.25398.0 <10.0.25398.2274
Microsoft · Windows 11 Version 22H3version=10.0.22631.0 <10.0.22631.6936
Microsoft · Windows 11, version 26H1version=10.0.28000.0 <10.0.28000.1836
Microsoft · Windows 11 Version 23H2version=10.0.22631.0 <10.0.22631.6936
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.5020
Microsoft · Windows Server 2025version=10.0.26100.0 <10.0.26100.32690

Published CVSS scores

7.0Microsoft CorporationCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-415Double Free
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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