Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAuthenticate as unprivileged local user
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DeliveryTrigger LUAFV file operation
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ExploitExploit race condition window
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ExecutionSwap file between checks
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ImpactAchieve privilege escalation
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture TOCTOU prevention
|
| Exploitation Conditions | Local user account required; Windows LUAFV (Low-Level User Account Filesystem Virtualization) must be active; precise timing of file system operations between access check and use required; exploitability depends on system load and CPU scheduling behavior. |
| Impact | Real-world risk is moderate despite the 7.0 CVSS score. The CVSS vector indicates local-only attack surface (AV:L), high complexity requiring precise timing (AC:H), and low-privilege authenticated access (PR:L). These constraints significantly limit mass exploitation scenarios compared to remote or low-complexity vulnerabilities. No EPSS score provided, but the high attack complexity and local-only vector typically correlate with lower exploitation probability in automated attack frameworks. No public exploit identified at time of analysis, and CISA KEV status not confirmed, indicating no evidence of active in-the-wild exploitation. However, TOCTOU vulnerabilities are well-understood primitives in Windows kernel exploitation, and motivated attackers with local access could develop reliable exploits given sufficient resources. The SSVC framework would likely classify this as 'attend' priority rather than 'immediate' - the vulnerability enables complete local system compromise (technical impact: total), but requires existing authenticated access and is not automatable due to race timing requirements. Patch availability from Microsoft across all supported platforms significantly reduces risk for organizations with mature patch management. Priority should increase in environments where local attackers are a primary threat model (shared workstations, terminal servers, compromised user accounts in APT scenarios). |
| Exploit ScenarioDerived | An attacker with valid domain credentials compromises a standard user account through phishing and establishes persistence on a Windows 11 workstation. Leveraging this authenticated low |
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Alert meAnalysisAIv1 – Apr 14, 2026
Windows LUAFV driver privilege escalation via TOCTOU race condition allows authenticated local attackers with low privileges to gain SYSTEM-level access across all supported Windows 10, Windows 11, and Windows Server versions (2012 through 2025). The vulnerability requires high attack complexity to exploit the narrow timing window between security checks and file operations. Vendor-released patch available across all affected platforms. No public exploit identified at time of analysis, though th
Earlier versions of this analysis (1)
Windows LUAFV driver privilege escalation via TOCTOU race condition allows authenticated local attackers with low privileges to gain SYSTEM-level access across all supported Windows 10, Windows 11, and Windows Server versions (2012 through 2025). The vulnerability requires high attack complexity to exploit the narrow timing window between security checks and file operations. Vendor-released patch available across all affected platforms. No public exploit identified at time of analysis, though the 7.0 CVSS score reflects significant post-exploitation impact (complete confidentiality, integrity, and availability compromise).
RemediationAI
Apply Microsoft security updates immediately to patch the LUAFV race condition. For Windows 10 1607, update to build 10.0.14393.9060 or later. For Windows 10 1809, update to build 10.0.17763.8644 or later. For Windows 10 21H2 and 22H2, update to builds 10.0.19044.7184 and 10.0.19045.7184 respectively. Windows 11 22H3 and 23H2 require build 10.0.22631.6936 or later, while 24H2 and 25H2 require builds 10.0.26100.32690 and 10.0.26200.8246 respectively. Windows 11 26H1 requires build 10.0.28000.1836 or later. Windows Server 2012 and 2012 R2 require builds 6.2.9200.26026 and 6.3.9600.23132 respectively. Windows Server 2016, 2019, 2022, and 2025 require builds 10.0.14393.9060, 10.0.17763.8644, 10.0.20348.5020, and 10.0.26100.32690 respectively. Deploy patches through Windows Update, WSUS, or SCCM following standard change management procedures. No effective workarounds exist for kernel-level TOCTOU conditions without disabling LUAFV entirely, which would break UAC virtualization for legacy applications. Detailed patch information available at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-27929.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 36 packages in microsoft, euvd
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Technical ContextAI · show details
Windows LUAFV (LUA File Virtualization) is a kernel-mode filter driver implementing User Account Control (UAC) file and registry virtualization for legacy applications running under standard user contexts. This CWE-367 time-of-check time-of-use race condition occurs when LUAFV performs security validation on a file object, but an attacker can modify the target between the authorization check and the actual file operation. The timing window allows substitution of a privileged resource (such as a system file or registry key) after LUAFV validates access but before the operation executes. Successful exploitation requires precise timing to win the race condition, accounting for the AC:H (high attack complexity) rating. The vulnerability affects the core Windows security boundary between standard user and elevated contexts, making it a critical local privilege escalation vector across CPE-identified products spanning Windows 10 1607 (released 2016) through Windows 11 26H1 and Windows Server 2025.
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Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Time-of-check time-of-use (toctou) race condition in Windows LUAFV allows an authorized attacker to elevate privileges locally.
Executive ViewAI
CVE-2026-27929 is a Windows LUAFV driver privilege escalation vulnerability affecting all Windows 10, Windows 11, and Windows Server 2012-2025 installations, enabling authenticated local users to gain SYSTEM-level access and achieve full system compromise. This vulnerability requires a valid user account but presents material risk to organizations with shared workstations, service accounts, or where insider threats are a concern, necessitating prompt patching to prevent lateral movement and privilege escalation attacks.
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Threat Intelligence Overview
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.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.
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