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Windows 11 24h2 CVE-2026-21221

HIGH
Race Condition (CWE-362)
2026-01-13 secure@microsoft.com
Information Disclosure Race Condition Microsoft Windows 11 24h2 Windows 11 25h2 Windows Server 2025
7.0
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
    Gain local access with user privileges
  2. Exploit
    Trigger race condition in camsvc capability check
  3. Execution
    Bypass synchronization mechanism
  4. Impact
    Escalate to elevated privileges

Vulnerability Assessment

Weakness
CWE
CWE-362
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V15 - Secure Coding and Architecture Concurrency control, locking
MITRE ATT&CK

1 technique across 1 tactic: 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 on the system. Race condition window in Capability Access Management Service (camsvc) during concurrent capability access requests. Requires precise timing to exploit synchronization gap between privilege validation and resource access.
Impact

CVSS 7.0 (HIGH). Attack vector: Local. Complexity: High. 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 11 and Windows Server 2025 Capability Access Management Service results from a race condition in resource synchronization, enabling authenticated local users to gain elevated system privileges. The vulnerability affects multiple recent Windows versions (24h2 and 25h2) and currently lacks a patch. No public exploit code has been disclosed, though the attack requires local access and moderate complexity to execute.

Earlier versions of this analysis (1)
v1 Mar 12, 2026 - 21:54 CVSS 7.0

Concurrent execution using shared resource with improper synchronization ('race condition') in Capability Access Management Service (camsvc) allows an authorized attacker to elevate privileges locally. [CVSS 7.0 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

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Technical ContextAI · show details

Classified as CWE-362 (Race Condition). Affects the Capability Access Management component of Windows 11 24H2. Concurrent execution using shared resource with improper synchronization ('race condition') in Capability Access Management Service (camsvc) 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 7.0 HIGH
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
ENISA EUVD HIGH

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

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

DescriptionCVE.org

Concurrent execution using shared resource with improper synchronization ('race condition') in Capability Access Management Service (camsvc) allows an authorized attacker to elevate privileges locally.

Executive ViewAI

Why It Matters

CVE-2026-21221 presents moderate security risk, a race condition vulnerability rated CVSS 7.0. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and consider compensating controls in the interim.

Business Impact: Moderate
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
0.0%
Top 86% exploitable
Threat Intel
1
1 source
Data Quality
4 sources
Confidence: Medium
NVD CVE.org EPSS NCSC-NL 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

Exploitation· derived
None
System Exposure· derived
Small
Automatable· derived
No

Priority Score

40
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +35
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: +5

Attack Technique

Information Disclosure MEDIUM

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

Race Condition MEDIUM

Race conditions occur when multiple concurrent requests exploit the brief time gap between checking a condition and acting upon it (TOCTOU - Time of Check, Time of Use).

Affected Products (CPE)CVE.org

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_server_2025:*:*:*:*:*:*:*:*

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Same weakness CWE-362 – Race Condition

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References

Advisories & patches
ADVISORY https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21221 ADVISORY https://vuldb.com/vuln/340848

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