CVE-2026-83721 - Vulnerability Details

- Win32k Elevation of Privilege Vulnerability

Description

Use after free in Windows Win32K allows an authorized attacker to elevate privileges locally.

Published: 2026-10-13

Score: 7.8 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

A use‑after‑free in the Windows Win32K kernel component allows an attacker with local access and sufficient privileges to manipulate freed memory, enabling them to raise their privileges on that machine.

Affected Systems

Microsoft Windows 11 versions 24H2, 25H2, 26H2 and 26H1, as well as Windows Server 2025, including Server Core installations are affected.

Risk and Exploitability

The vulnerability has a CVSS score of 7.8, indicating a high severity. EPSS is not available, so the exploit probability is unknown, but the issue is not listed in CISA’s KEV catalog. The attack vector is local, requiring an authorized attacker with user-level access; exploitation could elevate the attacker to system-level privileges, compromising confidentiality, integrity and availability of the affected host.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Microsoft

Windows 11 Version 24H2

affected

Version	Status	Constraints
`10.0.26100.0`	affected	< 10.0.26100.9711

Microsoft

Windows 11 Version 25H2

affected

Version	Status	Constraints
`10.0.26200.0`	affected	< 10.0.26200.9711

Microsoft

Windows 11 version 26H1

affected

Version	Status	Constraints
`10.0.28000.0`	affected	< 10.0.28000.3231

Microsoft

Windows 11 Version 26H2

affected

Version	Status	Constraints
`10.0.26300.0`	affected	< 10.0.26300.9711

Microsoft

Windows Server 2025

affected

Version	Status	Constraints
`10.0.26100.0`	affected	< 10.0.26100.33650

Microsoft

Windows Server 2025 (Server Core installation)

affected

Version	Status	Constraints
`10.0.26100.0`	affected	< 10.0.26100.33650

Configuration 1 [-]

OR	cpe:2.3:o:microsoft:windows_11_24h2:::::::arm64:*
	cpe:2.3:o:microsoft:windows_11_24h2:::::::x64:*
	cpe:2.3:o:microsoft:windows_11_25h2:::::::arm64:*
	cpe:2.3:o:microsoft:windows_11_25h2:::::::x64:*
	cpe:2.3:o:microsoft:windows_11_26h1:::::::arm64:*
	cpe:2.3:o:microsoft:windows_11_26h1:::::::x64:*
	cpe:2.3:o:microsoft:windows_11_26h2:::::::arm64:*
	cpe:2.3:o:microsoft:windows_11_26h2:::::::x64:*
	cpe:2.3:o:microsoft:windows_server_2025:::::::x64:*

No data.

Vendor Product Confidence Versions

Microsoft

Windows 11 24h2

100%

Version	Status	Scheme	Platform
`[10.0.26100.0,10.0.26100.9711)`	affected	generic	['arm64-based_systems', 'x64-based_systems']

Microsoft

Windows 11 25h2

100%

Version	Status	Scheme	Platform
`[10.0.26200.0,10.0.26200.9711)`	affected	generic	['arm64-based_systems', 'x64-based_systems']

Microsoft

Windows 11 26h1

100%

Version	Status	Scheme	Platform
`[10.0.28000.0,10.0.28000.3231)`	affected	generic	['arm64-based_systems', 'x64-based_systems']

Microsoft

Windows 11 26h2

100%

Version	Status	Scheme	Platform
`[10.0.26300.0,10.0.26300.9711)`	affected	generic	['arm64-based_systems', 'x64-based_systems']

Microsoft

Windows 11 Version 26h2 For Arm64-based Systems

100%

Version	Status	Scheme	Platform
`—`	affected	—	—

Microsoft

Windows Server 2025

100%

Version	Status	Scheme	Platform
`[10.0.26100.0,10.0.26100.33650)`	affected	generic	['x64-based_systems']

Microsoft

Windows Server 2025 (server Core Installation)

100%

Version	Status	Scheme	Platform
`[10.0.26100.0,10.0.26100.33650)`	affected	generic	['x64-based_systems']

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Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Apply the latest cumulative Windows update that includes the fix for CVE‑2026‑83721 from Microsoft.
Enable User Account Control at least to the highest level and limit local user privileges by restricting non‑administrative tasks to a dedicated account.
Until the patch is available, isolate the vulnerable device from the network or run it in a controlled environment to limit exposure.

Generated by OpenCVE AI on October 14, 2026 at 05:06 UTC.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00353.

Exploitation none

Automatable no

Technical Impact total

References

Link	Providers
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83721

History

Thu, 29 Oct 2026 20:00:00 +0000

Type	Values Removed	Values Added
CPEs		cpe:2.3:o:microsoft:windows_11_24h2:::::::arm64:* cpe:2.3:o:microsoft:windows_11_24h2:::::::x64:* cpe:2.3:o:microsoft:windows_11_25h2:::::::arm64:* cpe:2.3:o:microsoft:windows_11_25h2:::::::x64:* cpe:2.3:o:microsoft:windows_11_26h1:::::::arm64:* cpe:2.3:o:microsoft:windows_11_26h1:::::::x64:* cpe:2.3:o:microsoft:windows_11_26h2:::::::arm64:* cpe:2.3:o:microsoft:windows_11_26h2:::::::x64:* cpe:2.3:o:microsoft:windows_server_2025:::::::x64:*

Sun, 18 Oct 2026 10:30:00 +0000

Type	Values Removed	Values Added
First Time appeared		Microsoft windows 11 24h2 Microsoft windows 11 25h2 Microsoft windows 11 26h1 Microsoft windows 11 26h2 Microsoft windows Server 2025 (server Core Installation)
Vendors & Products		Microsoft windows 11 24h2 Microsoft windows 11 25h2 Microsoft windows 11 26h1 Microsoft windows 11 26h2 Microsoft windows Server 2025 (server Core Installation)

Tue, 13 Oct 2026 22:30:00 +0000

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}`

Tue, 13 Oct 2026 19:15:00 +0000

Type	Values Removed	Values Added
Description		Use after free in Windows Win32K allows an authorized attacker to elevate privileges locally.
Title		Win32k Elevation of Privilege Vulnerability
First Time appeared		Microsoft Microsoft windows 11 24h2 Microsoft windows 11 25h2 Microsoft windows 11 26h1 Microsoft windows 11 Version 26h2 For Arm64-based Systems Microsoft windows Server 2025
Weaknesses		CWE-416
CPEs		cpe:2.3:a:microsoft:windows_11_version_26h2_for_arm64-based_systems:::::::: cpe:2.3:o:microsoft:windows_11_24H2:::::::arm64:* cpe:2.3:o:microsoft:windows_11_25H2:::::::arm64:* cpe:2.3:o:microsoft:windows_11_26H1:::::::x64:* cpe:2.3:o:microsoft:windows_server_2025::::::::
Vendors & Products		Microsoft Microsoft windows 11 24h2 Microsoft windows 11 25h2 Microsoft windows 11 26h1 Microsoft windows 11 Version 26h2 For Arm64-based Systems Microsoft windows Server 2025
References		https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83721
Metrics		cvssV3_1 `{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C'}`

Subscriptions

Microsoft Windows 11 24h2 Windows 11 24h2 Windows 11 25h2 Windows 11 25h2 Windows 11 26h1 Windows 11 26h1 Windows 11 26h2 Windows 11 Version 26h2 For Arm64-based Systems Windows Server 2025 Windows Server 2025 (server Core Installation)

MITRE

Status: PUBLISHED

Assigner: microsoft

Published: 2026-10-13T19:00:52.459Z

Updated: 2026-10-31T18:08:51.169Z

Reserved: 2026-08-31T22:49:39.365Z

Link: CVE-2026-83721

Vulnrichment

Updated: 2026-10-13T20:33:14.205Z

NVD

Status : Analyzed

Published: 2026-10-13T19:20:17.027

Modified: 2026-10-29T19:51:38.383

Link: CVE-2026-83721

Redhat

No data.

OpenCVE Enrichment

Updated: 2026-10-18T10:15:06Z

Weaknesses

CWE-416
Use After Free

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Exploitation none

Automatable no

Technical Impact total

Subscriptions

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