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Windows 11 24h2 CVE-2026-20870

HIGH
Use After Free (CWE-416)
2026-01-13 secure@microsoft.com
Denial Of Service Use After Free Memory Corruption Microsoft Windows 11 24h2 Windows 11 25h2 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
    Authenticate as local user
  2. Exploit
    Trigger use-after-free in Win32K ICOMP
  3. Execution
    Dereference freed memory
  4. Impact
    Execute arbitrary code in kernel context

Vulnerability Assessment

Weakness
CWE
CWE-416
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Memory lifecycle management
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Exploitation Conditions

Local user account required; Windows Win32K ICOMP component must be active. Attacker needs existing logon session (PR:L) on the target system.
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 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Privilege escalation in Windows Win32K ICOMP component via use-after-free memory corruption affects Windows 11 (24h2, 25h2) and Windows Server 2025. An authenticated local attacker can exploit this vulnerability to gain SYSTEM-level privileges with no user interaction required. Currently no patch is available and exploitation requires local access with user-level permissions.

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

Use after free 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_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_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 3 packages in microsoft

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

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Technical ContextAI · show details

Classified as CWE-416 (Use After Free). Affects Windows 11 24H2. Use after free 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

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

Executive ViewAI

Why It Matters

Organizations using Use after free in Windows Win32K - ICOMP face notable risk from CVE-2026-20870, a use-after-free vulnerability 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) Enable ASLR and DEP where available; (2) Implement network segmentation; (3) Monitor for exploitation indicators.

Threat Intelligence Overview

EPSS Score
0.0%
Top 92% 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 0.0%
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

Use After Free HIGH

Use-after-free vulnerabilities occur when a program continues to access memory through a pointer after that memory has been deallocated.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)CVE.org

cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*

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Same weakness CWE-416 – Use After Free

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CVE-2015-5122 CRITICAL POC
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CVE-2013-2551 HIGH POC
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Same technique Denial Of Service

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CVE-2011-2462 CRITICAL POC
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CVE-2012-1889 HIGH POC
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CVE-2014-1761 HIGH POC
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CVE-2011-0609 HIGH POC
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References

Advisories & patches
ADVISORY https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20870 ADVISORY https://vuldb.com/vuln/340800

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