CVE-2026-83879 in Windows
Summary
by MITRE • 10/14/2026
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Overlay Filter allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves a race condition within the Windows Overlay Filter subsystem, specifically arising from concurrent access to shared resources without proper synchronization mechanisms. This flaw represents a classic concurrency issue where multiple threads or processes attempt to read and write data simultaneously, leading to unpredictable behavior due to non-deterministic execution ordering. In this specific context, the lack of atomic operations or mutex locks allows an attacker who has already gained authorized local access to manipulate the state of shared resources in a way that bypasses intended security controls. The core technical flaw lies in the failure to enforce mutual exclusion during critical sections of code where resource integrity is paramount, creating a window of opportunity for privilege escalation.
From a classification perspective, this vulnerability aligns with CWE-362, which defines concurrent execution using shared resources with improper synchronization as a race condition. This category highlights scenarios where software does not properly coordinate access to shared data structures, leading to state corruption or logic bypasses. Furthermore, the exploitation of such a flaw for local privilege escalation maps directly to MITRE ATT&CK technique T1068, which covers Exploitation for Privilege Escalation. The attacker leverages this timing vulnerability to transition from a lower-privileged user context to that of SYSTEM or another high-privilege account, effectively compromising the confidentiality and integrity of the operating system by gaining unrestricted control over critical resources.
The operational impact of this race condition is severe because it allows an authenticated adversary to escalate privileges on the affected Windows systems. Once local access is established through any initial vector such as phishing, credential theft, or network exploitation, the attacker can exploit this synchronization flaw to execute arbitrary code with elevated permissions. This undermines the principle of least privilege and compromises the overall security posture of the environment. The ability to bypass authentication checks or manipulate system states due to race conditions makes these vulnerabilities particularly dangerous in multi-user environments where isolation between processes is critical for maintaining stability and security.
Mitigation strategies primarily involve applying vendor-supplied patches that address the underlying synchronization issues within the Windows Overlay Filter component. Administrators should ensure that all systems are updated with the latest cumulative updates provided by Microsoft, which typically include fixes for such concurrency flaws alongside other known vulnerabilities. Additionally, implementing strict access controls and monitoring for unusual process behavior can help detect attempts to exploit race conditions before they succeed. Since this vulnerability requires local authorized access, enforcing strong authentication policies and limiting user privileges where possible reduces the attack surface available to potential adversaries seeking to leverage this flaw for privilege escalation.