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Windows 11 23h2 CVE-2026-20811

HIGH
Untrusted Pointer Dereference (CWE-822)
2026-01-13 secure@microsoft.com
Information Disclosure Microsoft Windows 11 23h2 Windows 11 24h2 Windows 11 25h2 Windows Server 2022 Windows Server 2022 23h2 Windows Server 2025
7.8
CVSS 3.1 · Vendor: microsoft
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Login as unprivileged user
  2. Delivery
    Craft malicious ICOMP resource with type confusion
  3. Exploit
    Trigger Win32K handler
  4. Execution
    Exploit type mismatch in resource validation
  5. Persist
    Execute kernel code
  6. Impact
    Achieve SYSTEM privileges

Vulnerability Assessment

Weakness
CWE
CWE-822
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Untrusted pointer prevention
Exploitation Conditions

Local system access required. Attacker must possess valid user credentials (PR:L). Windows Win32K ICOMP (Icon Component) handler must process attacker-supplied resource objects. No user interaction needed. Vulnerable on default Windows installations with ICOMP enabled.
Impact

CVSS 7.8 (HIGH). Attack vector: Local. Complexity: Low. Privileges required: Low. User interaction: None. Exploitable via local access.
Exploit ScenarioDerived

An attacker could exploit this vulnerability to compromise the affected system.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Local privilege escalation in Windows Win32K (ICOMP) via type confusion allows authenticated users to gain system-level access on Windows 11 and Windows Server 2025. The vulnerability affects multiple recent Windows versions with no available patch, requiring immediate mitigation strategies for at-risk environments. Exploitation requires local access but no user interaction, making it a significant risk for multi-user systems.

Earlier versions of this analysis (1)
v1 Mar 12, 2026 - 21:54 CVSS 7.8

Access of resource using incompatible type ('type confusion') in Windows Win32K - ICOMP allows an authorized attacker to elevate privileges locally. [CVSS 7.8 HIGH]

RemediationAI

Monitor vendor advisories for a patch.

Affected Packages

microsoft windows_11_version_23h2_10_0_22631_6491 fix: Windows 11 Version 23H2 for ARM64-based Systems 10.0.22631.6491, Windows 11 Version 23H2 for x64-based Systems 10.0.22631.6491
microsoft windows_11_version_24h2_10_0_26100_7623 fix: Windows 11 Version 24H2 for ARM64-based Systems 10.0.26100.7623, Windows 11 Version 24H2 for x64-based Systems 10.0.26100.7623
microsoft windows_11_version_25h2_10_0_26200_7623 fix: Windows 11 Version 25H2 for ARM64-based Systems 10.0.26200.7623, Windows 11 Version 25H2 for x64-based Systems 10.0.26200.7623
microsoft windows_server_2022_10_0_20348_4648 fix: Windows Server 2022 10.0.20348.4648, Windows Server 2022 (Server Core installation) 10.0.20348.4648
microsoft windows_server_2022_23h2_edition_10_0_25398_2092 fix: Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.2092
microsoft windows_server_2025_10_0_26100_32230 fix: Windows Server 2025 10.0.26100.32230, Windows Server 2025 (Server Core installation) 10.0.26100.32230

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 6 packages in microsoft

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Technical ContextAI · show details

Affects Windows 11 23H2. Access of resource using incompatible type ('type confusion') in Windows Win32K - ICOMP allows an authorized attacker to elevate privileges locally.

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

Vendor (microsoft) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from Vendor (microsoft) · only source for this CVE.

CVSS VectorVendor: microsoft

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

Access of resource using incompatible type ('type confusion') in Windows Win32K - ICOMP allows an authorized attacker to elevate privileges locally.

Executive ViewAI

Why It Matters

CVE-2026-20811 presents notable security risk rated CVSS 7.8. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and consider compensating controls in the interim.

Business Impact: High
Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.

Threat Intelligence Overview

EPSS Score
0.1%
Top 77% exploitable
Data Quality
3 sources
Confidence: Low
NVD CVE.org EPSS VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No
Human Impact
High

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Affected Products (CPE)CVE.org

cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*

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References

Advisories & patches
ADVISORY https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20811 ADVISORY https://vuldb.com/vuln/340747

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